There are two sides of the aisle on the whole tristana ezreal ignoring CC shenanigans (and its more than just those two, it's really anyone with a dash that has an animation time).
On one side, it does feel like supreme shit when something like this happens:
For the blitzcrank player, getting a hook is pretty much 90% of your usefulness. To hit it and then be bitch slapped by game coding because tristana happened to queue her jump after the fact feels awful.
On the other side, some people argue that it was an intended mechanic and even riot came out to support the notion that the mechanic is in fact intended (which I question if they really DO think that or dont want to go through the coding hassle of fixing it).
My issue with this argument is that riot seems to play favorite with frustrating and seemingly unintentional mechanics.
Yeah, that and every other aoe like it (cho w, kassadin E, etc.) got fixed. So why would riot play favorites with dashes ignoring CC effects?