There’s no such thing as a free lunch…..
Good point, but you really shouldn’t try eating a pair of Carbon rims, or aluminium for that matter, whatever you paid.
When you think about it, it’s probably just an extra couple of hundred quid on the actual COGs for the bike, obviously they’d normally supply a wheelset with Al rims by default, if they’re paying more than ~£100 per carbon rim wholesale from the far east I’d be surprised, otherwise there’s not much difference.
It’s not a bad loss leader “Worth £1149” just means the RRP that mugs pay, but the actual dent to margin wouldn’t be that much, possibly a good deal of you’re after a new MTB.