Actually, working on a jump feature that has any sort of use can slow things down because while there are separate teams they work together, and if SE wants to make sure jump absolutely has to be in the game and has to work it'll push the update back till they get everything flowing properly.
It hasn't slowed them down. The'yve sill managed to push out huge patches while having all kinds of things like animations for jumping (and lots of other things), riding goobbues, and all sorts of other things. Anything that adds something to the game with some concievable use is not slowing them down or wasting their time. It's contributing something.