I want to make sure this is clear, this is NOT an optional rule in the PHB or elsewhere. This is a default rule available for everyone in the PHB, it not a "ask your DM for permission" sort of thing.
And now that backgrounds do something other than provide skills, it is a good time to unlock background skills... yes, you can still have the "suggested" ones... but they should be free to be changed.
Also, locking the party at the end of the first act, is one of the worst mistakes they could make in this game, see my thread on the topic if oyu havent already... it is bad for the game, more difficult to write, more time consuming to write, bad for the players, bad mechanically... and even bad for Larian for there company image (it will make them look like a one-trick pony)
But yeah, LET US CHOSE WHICH SKILLS WE HAVE WITH OUR BACKGROUND!