The building inspector can't see all the people you're making homeless right now by creating ever more expensive building codes. The permitting office doesn't see the good food people can't buy their children because they're spending more on their mortgage. The code enforcement officer doesn't see the person who ended up missing finding cancer early because their gas tank was empty and they couldn't book a doctor's appointment after increased inspecting and architectural requirements. People just see "bad thing happened in house because bad codes, spend more money that gets ripped away from other things that make us safe."
And that's part of the trickery involved here. People say "look that one guy died in that house so we need to require stricter code here." They're not noticing the freezing homeless people that died because housing become $X dollars more expensive and they lost the musical chairs game. Sure the homeless guy wasn't going to buy a brand new house, but through the substitution effect across a wide swath of society eventually down the chain it does filter down to everyone ultimately affecting their access to housing. And hey, added bonus, current homeowners property is also worth more when building becomes more expensive so why not juice that one housing related death for all you got even if you know saving that one in a million rich person's life ends with 2 more dead homeless people or whatever.
The ability for voters, already homed, to just change up the codes on everyone while not having their own homes subjected creates a cruel moral hazard and socially bifurcating effect. The guy that gets in early comes in and gets his, then says fuck you, you have to play by different rules.
I'm not saying the houses should be torn down. I'm saying any updates should put situation where homeowner voters are subject to their own medicine. I don't think they'll choose to tear down the houses. No they might decide after all "hey good enough for me, good enough for you."
As for "can't build with X thing they did/didn't have before." Well you can update the codes to allow both the old and new method for something. That would satisfy conditions for both standing and new construction without uniform enforcement causing old houses to be demolished.
It's honestly kind of insane I've had a couple people basically suggest that if the rules be applied evenly, they're going with the "go and tear down houses when code is updated and see how quick we can make everyone homeless" option to pick up their toys and go home rather than give others the same chance they had by allowing the old ways in the code. That's the only way I can make out you would seriously think people would end up homeless.