All manufacturers offer “customisation” as you call it, most just call it options, even Lexus gives you option packs.
All BMW are doing is giving buyers of secondhand vehicles the choice to upgrade to options that were never picked by the original buyer, I really don’t see the down side, sure it would be nice to have a buy outright option but the if you don’t keep cars that long your may well be paying half the cost for the next owner.