Is Flashing-to-move-the-AOE actually intended behavior?
I always assumed it was a bug/exploit, and I do not understand how it could be considered intended since it bypasses the intended range/reaction windows of abilities. I'm pretty certain it was fixed super fast when Nunu could Flash/Lantern/get Rocket Grabbed to move his ultimate's detonation to center on the new location, so what gives on Shadow Dash and Body Slam? (And the many others, I'm sure).
Virtually every Gragas and Shen over the weekend employed this "feature" and the casters commented on it like it was a feature of their kits and was well executed.
If they Flashed to get in range and then used the ability - that's fine; but I do not see how it's fair that a player can purposefully miss/under-shoot the ability and then just flash at the end to "stretch" its area-of-effect to guarantee it hits a target. This can be used to even have the ability move at obtuse angles from the original line-of-effect...
"Oh I missed/you dodged? Nah - I've got my Flash up!"
https://youtu.be/SFbgWHz3ous?t=19m41s
Gragas missed his Body Slam versus Sivir in the UOL vs H2K, but Flashed and stunned her anyway. The fact he intended to do this doesn't change the fact that the ability missed, and it's the fact the ability can be intentionally missed that makes it look like an exploit/bug.