You don't want closing the lid to automatically sleep the system?
As a matter of fact, I don't. But that's irrelevant. That kind of stuff was already handled by existing stuff. You could make it so that closing the lid locks, sleeps, or locks and sleeps, all within programs that already existed and worked.
You think it's better if the desktop environment includes the code to put the computer to sleep? I thought you didn't want monolithic code, you want code split into separate areas of concern?
I never said the DE itself should handle anything low-level with sleep, just that it would tell some other program to put the computer to sleep. Programs which already existed and worked.
Many parts of systemd are just solutions looking for problems. Same as Pulse "it works except when it doesn't" Audio, 99% of systems have no need for Pulse, and there are probably more machines that run into bugs with Pulse with the stock config than without Pulse.