what about when your kids come to visit? Surely nicer to be in a villa with a yard/space for them to have room than bunking in on the sofa? (guess it would depend how long they are here for)
Also on the co-acc side is that it's paid for, no need to worry about rent hikes and should your situation change in future you still have access to a villa. If you opt out and things change (best case wife wants to come back, worst case you part ways) you'll still be stuck renting and possibly the allowance would no longer let you to rent a villa if you so wished to get back into one for whatever reason.... very possible with the rents going up as they are...
(Just a view from someone who shuttled between parents' places as a kid and appreciated having my own room when visiting Dad!)