The idea that ornament is a crime has done more visual damage to our buildings than any other single factor in my opinion, the fact we still regularly poll as preferring Victorian and Georgian buildings is an indictment of those responsible for our stock of them; I prefer those buildings but it depresses me that we've made things worse rather than better aesthetically for the last century or so when we didn't have to.
Modern new builds are bleak things for the most part; oppressively low ceilings, tiny postage-stamp sized windows as the enshittified way to comply with energy efficiency legislation, styling which looks like it was done by ChatGPT, and build quality that makes British Leyland cars look like epitomes of careful manufacturing. While if it were up to me I'd replace our discretionary planning system with a rules-based one and remove a lot of incumbent NIMBY vetos, I can see why NIMBYs exist in such enormous numbers given the race to rock bottom on everything except price when it comes to housing.