This has come up a few times. This is a gameplay feature. If you raise your repair skill to at least 120, repair will become instantaneous.
I don't know if you can do that in the main game (or even with Islands of Ice and Fire installed), but Zarista Games' expansions are coming and you'll surely be able to reach that value in one of them.

As for this "gameplay feature", I agree with you that it's not that good. However at this point in time we'll not add or change anything in the game (except fix serious bugs). And it's not
that bad either.
