I think the party is fine but gifts that often no way!!
A plant or something like that maybe but def not new things, what do they do with all the old things they have???
yes tacky even more so if they expect gifts!
I would think it is very odd they they "think" they need a party like that with every house. Strange and a lot wasteful. I would go to the party and bring them a bunch of gifts with things that are reused, re purposed...etc now that would be funny. I would also make up a cute clever card to go with the gift. :)