I guess you dont play a lot jedi. It is funny, many times jedi is the one in biggest danger with nades. Lets take gungan style - dude for an example. He does not throw the nade unless somebody is there. So what are you supposed to do, just run behind the corner everytime you see him? Yeah lets use 5 min of the round for that. Add 3 more nade thrower EACH 2 lives then thats a lot of nades to push. What if I dont push and jump around? Sometimes yeah I have to but it is not always and option or should I let the gunners die? Neither can I trust other jedi since many times they dont know what they are supposed to do.
Btw throwin nades in dotf main is one of the easiest things. Just throw em at a hard angle so when you push the ceiling bounces em somewhere else than they are supposed to be going. Add there random dodgin and takin cover and sniping em isnt the easiest thing to do (besides, didnt you just say you should run if you see a nademan but then you say they get sniped easily, kinda contradicting yourself there)
I didn't say you should run when you see a grenadier, I said you should run when he is preparing to throw a nade. That means, when you hear that beeping sound the nade makes when he presses the button, or when you see him switching to a grenade in your vicinity. Why should you care if a grenadier is throwing a nade from far away? In those situations you can always run away. I'm not contradicting myself, when the grenadier is far away you can freely snipe him. They have to cover some ground in DotF main before they can be a threat to you so you can snipe them then. I don't know, I might just be good in dodging nades, it is usually my teammates that die and I survive when a nade is thrown, some other people might be worse at dodging them and it poses a problem to them. To dodge a nade you have to run the opposite of the direction the nade is going, but you also have to predict where it will move if there is some obstacle in its way and it bounces off. You can also run the same direction of the grenade if it is thrown at a safe distance and it won't reach you where you are heading. You also have to take into account any cover around you. A nade can't hit you if there is some obstacle between you and it, even if it detonates 10 cm from you. Any kind of box, small or big obstacle for cover helps. Another help can be the special traits of your class, like ARC lounge/Hero dash/Push/Speed/etc., that can get you out of the harm's way.
On the other hand, when throwing a grenade there are certain trickshots that can help you land it as you wish:
1. If the enemy is approaching you, you aim directly upwards above you, throw a nade at full velocity, and then run backwards away from the attacker. As the enemy approaches towards you chasing you, the grenade will land on them and detonate them. This is especially useful versus saberists, as they have to approach you in melee range and don't have much HP like Wookies, for example. This is also an excellent way to counter Push as a grenadier, as when you throw a nade so high up it will exit the saberists camera view and Push radius (unless they follow it with their camera), and they may think it has gone behind them. This works best when the ceiling isn't low as to bounce the grenade off before it has reached its peak.
2. When there is a surface behind the attacker that can bounce the grenade back towards you when you throw it, like a wall, for example, you can throw a nade to bounce off of it and to trick the enemy. This is useful when the enemy is approaching you, you throw a nade behind them at full speed and they think it's gone while they are coming towards you, but it bounces back off the wall you've thrown it at following them in their tracks behind their back and detonating them. You can make it even better if you throw it from behind some cover to make it more unpredictable and for it to have less chance to be Pushed. When you are at a corner between two corridors which are at 90 degrees, throwing it diagonally off some protruding wall segment where there is a 90 degrees angle will bounce it back towards you while you are hiding behind the cover in one of the corridors and the enemy is approaching from the other, having the same effect and detonating them. This can be used on portruding wall segments on DotF, for example.
3. Throw it where it will bounce back to the enemy when they Push it. As you said, when you throw it into DotF main ceiling it will bounce off the protruding arches back to the enemy when Pushed or towards another enemy. You can do this anywhere where there is an obstacle that can be found in the area between you and the enemy which can bounce the grenade back to them when they Push it. You have to throw it so that the grenade will be between the obstacle and the enemy when it is Pushed.
4. Throw it at the enemy so it bounces unpredictably. You can throw nades where it will bounce off of walls, ceiling, floor, and everywhere around multiple times as to confuse the enemy and make it harder for them to identify where the grenade exactly is, where it will go and where it will get Pushed when they Push it. Throwing it diagonally off of walls/ceiling into a corridor or a room like this can achieve this effect and it will bounce around. The one downside of this method is that it is also hard for you to know where the grenade will go.
5. Try to predict where an enemy will go and throw an unseen grenade in their way that will explode in the moment they come into its sight. This is useful when an enemy is chasing or approaching you too. You know that the enemy will go through a door and you can predict when (it's especially easy to predict if the enemy is going straight to you moving straight forward without turning around or stopping), so you throw a nade at the door where the enemy will pass, and it detonates in the moment the door opens and the unknowing-of-anything enemy is detonated. You can also throw a nade like this at a corner, at your side of the corner, for it to detonate when the enemy comes around that corner having the same effect, or throw it to detonate when it peeks behind a corner where you predict enemies will approach at that moment and not hear/see it until it's too late, like people do with Thermal Detonators in DotF main. The downside of this method is that it is very hard to predict exactly when the enemy will reach the point where your grenade will detonate, especially if you can't see them. It is basically a gamble, and you don't have many grenades.
6. You can throw a grenade directly into the enemy and it will bump into them and get stuck at their feet. This is then very hard to dodge/run away from (also because the grenade will suddenly and unpredictably change its speed to a halt) and they will get detonated.
The problem is that nades are very situational. You can't always land them as you wish and it is very hard to achieve, especially if the surrounding area isn't suited for that, like DotF hangar, for example; and also because you depend on whether or not the grenades will get Pushed and thus disabled. When you lose the nades you are completely useless if you are a grenadier. Some people then even kill themselves as to get grenades in their new life. You must also take into account that your nades can very easily kill your teammates, either when thrown unluckily, when an ally walks into them or when they get Pushed by an enemy or an ally. Plus, there is that thing that you don't get anything, no kill or assist, if someone Pushes your grenade and that the enemies can use your grenades to get kills with Push.