If by “aging 1981 apartment building” they mean an apartment building built in 1981, it is so frustrating to me that American buildings are essentially designed

If by “aging 1981 apartment building” they mean an apartment building built in 1981, it is so frustrating to me that American buildings are essentially designed for a useful life of ~30 years before they need to be replaced. Though there are maintenance costs to maintaining older buildings, other things being equal isn’t it better to maintain rather than rebuild? My personal preference for older buildings aside, aren’t some of the most desirable and high-value apartments well-preserved older buildings?