The only convincing argument I've heard for why islands are doable but housing isn't, is that the islands are samey as hell so they don't utilize as many resources as a unique house that has to be "on" and running at every moment's notice.
Do I ........ accept this limitation? Nope. I think at this point the multi billion dollar company can just buy more space to give players more wards. I swear to god people who don't even work there and know as little about SE's situation as you or I have been playing cover for Square for years while they've bungled the housing situation left and right. I think I've heard every excuse in the book for why this 2 billion dollar organization running one of the most successful and profitable MMORPGs of all time can't just acquire more resources to give the players the thing they advertised. Or why, failing that, they can't just listen to their community about its needs for 2 minutes and stop catering to an FC demographic that basically doesn't exist anymore. I swear SE really thinks FCs are like 50 happy people doing submarines together and not just 1 guy and his dozens of alts buying up multiple wards. Then islands come out and on day one are so popular that we can't get into our... houses/apartments. Hinting that they share the same resources. It was such a slap in the face, even if housing and islands don't use the same amount of resources necessarily.
On the topic of islands, people compare it to animal crossing but it's totally lacking in all the charm, customization, and multiplayer fun of animal crossing. Islands represent everything bad about animal crossing. All of the negative things that animal crossing fans put up with, like timegating and the feeling of "not a lot to do while I wait," is just the primary feature of islands, whereas in animal crossing it's the crap you push through to get to the good times. Island sanctuary doesn't have a good time. You just grind until you can unlock a new timegated feature. Then you wait for that feature to appear. It sits there and does nothing. Then you grind some more. That's it. And every milestone or so, they'll toss a new clothing item in to keep people doing it. We could've had so many other things in place of the development time this system took. I don't even want to think about it.