Bad point of view. It shouldn't be systemd's task to decide who is running properly and who is not. If a process lingers because of some bad behavior or bug, than that should be corrected, but assuming every process is an idiot and should be killed is very stupid. The default behavior should be - as it always was - that if a process is running after the user left, does so intentionally. Such decades old expected behavior should not be changed because of some idiot thinks everyone's usage patterns fits his own.
Well, it's a point of view, but not necessarily bad. Both points of view are valid:
Yours is:
a) Assume that processes which stay alive after logout are meant to be there, leading to a potentially unclean state after logout, if some random gnome/kde/etc. process did simply not exit
Systemd's is:
b) Assume all processes, which stay alive after logout are dead leftovers, always provide a clean slate.
Each has their up and downsides and I very much agree that the way the change was introduced was bad, because the release came without warning like a sledgehammer and changed existing behaviour. If screen and nohup were made systemd aware beforehand with a looooong introductory period and many warnings, this outcry would have been much much smaller.
When just looking at both options a) and b) without thinking about existing behaviour, I do think that b) is the better option. When logging out, I expect my system to be in a clean state and I, as a user, will never check for still running processes after logout.