Modern cars are often more work to repair. They're not particularly modular, and to the extent that they are, they often bury one module under several layers of others. It requires you to disconnect and move working parts and assemblies to uncover the broken one.
Modern cars also use replaceable assemblies to speed up repairs, but it also means that even for small problems like a damaged wire in a harness, you often have to rip out the entire system it is "inside" of and replace it completely. The manufacturer has tons of ways of requiring you to "over replace" parts like this on a modern vehicle.
> but why should they be?
That's not an excuse to make them as disposable as they've become. You can't use "the climate" to blindly turn this into a black and white issue.