Isn't that kind of use case what DCCP was designed for ?
Yes. You can show me a relative corner case. But in most cases you want TCP.
It's far from being a corner case. UDP is commonly used in multiplayer games to provide a channel for unreliable data.
If you want to go with that argument, why not go all the way and say that the common case is HTTP and the corner cases are everything else?
It still won't change the fact that application needs won't always match TCP exactly. And that's the whole point.
Would you rather wait for a transmission of the missing position update 1 sec ago or just forget about it and continue processing the next one ?
In this context, you'll prefer the second option. It will probably cause a visual glitch but the game can go on, and players will say "lag" :)