Yaws in and of themselves are necessary to be able to change the timing of your swings. Yaws can be annoying if someone is deliberately avoiding swinging into your cursor and manipulating their zones using movement, but at this point you are just losing to a more skilled duelist. Of course, this can be mitigated with distancing (counters almost always land if you both yaw correctly and walk away from your opponent), slaps, predictive PBs, etc.
The biggest issue, however, is having these extremely fast swings like dualies A halfswing and combos, where anyone fighting it is forced to be passive and predictively swing on certain timings, and simply hope that their swing will land. Dualies is the most egregious example, since it possesses both a near-instant halfswing (A counter/halfswing in facehug), fast combos, an instantly-hitting stab that is un-PBable and interrupts counterswings, and has alright range (at least, better than staff's range). When you combine all these tools with yaws, it makes it seem like yaws are the issue when they are at most an inconvenience for PBing, and are more a timing tool at the highest level that happen to complement near-instant swings.
The problem to target here is not swings that are fast when yawed (otherwise cyan swings would fit that same bill), but swings that do not require you to move your mouse to get ultrafast counters/halfswings, which lowers the skillcap and incentivizes facehug spam. Blue combos/halfswings, dualies A halfswing, dualies stab, and staff counters/halfswing stand out as the biggest offenders of this facehug "chainsaw" style, and even if you can beat most randoms who try to abuse these styles, a top tier blue or dualies is nonetheless a pain in the ass to fight, especially since they can get very fast hits without needing to turn or look very far from their opponent.
Regarding Tempest's patch, when I tried it in the spring, I would say that the biggest offenders to me are the dualies A halfswing and stab, and some of the new yellow counters are much too quick and do not sacrifice cursor position for a fast hit. Blue and staff have been tweaked to be slower on many of their abusive swings. The one exception to me would be Tempest's yellow A swing counter, since that does half damage and is relatively harmless in comparison to most swings.
The main message is: Yawing is a necessary mechanic, but you should have to sacrifice your cursor positioning and look away from your opponent to yaw, whether yawing faster or slower. If you can swing quickly without moving your cursor and have both fast swings and a ready defense, that's when the system needs to change.
tl;dr: when do I get a new computer so I can rant more about MB2