For some reason most members of the WBR feel that the only thing throws need is kb changes, when this really isn't the case. So far, no character has received a throw speed mod in any set, with the exception of when we were trying to fix certain CGs before we had access to the throw mod, which ended up failing miserably. And then long ago, before the WBR was formed, there was a movement to universally speed up throws by 1.1x, which ended up failing because of the resultant glitchiness. Let's face it, we've had some bad experiences with modding throw speed.
Of course, there's another bigger reason we don't use frame speed as much as we use kb mods. One of the biggest reasons the WBR has tended to stray away from modding frame speed is that frame speed lines right now are scarce to come by. We can't just put in as many as we choose, and are in fact limited by the code, so this is probably actually the primary reason we tend to stray from giving out frame speed adjustments to fix throws like this.
That said, there are truly some throws that just have too much lag to be useful, no matter how "good" of a trajectory they send at. And now that dthrow consistently combos into things, there's almost no good reason to use uthrow at all. This is definitely a case where it would've been better to cut off some winddown, and once we get the new frame speed engine, expect it to be a lot more likely to be implemented.