From what I have seen, most of the improvements have increased control and flexibility. Its odd to argue against a system that allows you the flexibility to set a program to run when any other system event is triggered, such as the NIC coming online.
The fact is, the ones who don't like systemd or polkit tend to be a certain percentage of the system administrator types (not all of them). Ironically, these who do most of the complaining have the skills to be able to configure the system how they want. Don't like polkit or systemd? Just configure your system not to use it. No one is stopping you. You can replace systemd with your own init system if you want. Use an older WM like fvwm and you wont have any problem, which you probably prefer anyway. There are many other WMs that dont have any dependancy on systemd, as well. I do agree that a program with a systemd dependancy should not refuse to run at all if systemd is not there, instead, only the systemd dependant features of it would be unavailable. if Gnome does not work this way, that is a valid point., Of course it is okay for gnome to hook systemd features, but if systemd is not there, the basic functionality should still work, just the systemd dependant features would be unavailable.
If systemd and polkit are not well documented and not configurable enough, I think that those are valuable points, these things should make our control and monitoring of the system easier, they should add more options and more logging facilities for expert users to keep an eye on things.
I seriously question the mentality of those who find the general concept of polkit or systemd unacceptable. For instance, it sort of makes sense that there ought to be some sort of an framework for IPC authorization, rather than a million incompatable systems, its better to have a well audited standard facility for that. It can also be handy to have a facility so that I can set up a program to be run when the IP address is asigned or just after another process starts or any other system event. To argue against having this functionality is just bizarre in my opinion and seems to be that these so called "experts" who argue against them want us to have less control over the system.
The basic system of Unix permissions while being suitable in many cases, can be more difficult to manage in others. What if i want to write some rules to say that a particular user should not have access to certain directories, or to say they should only have access to certain directories. Some sort of rule based system where you can define a set of rules that apply to that user can be better in some cases than the per file permissions.What if I want to apply such a set of rules to a single process when he process is run? The same thing goes. The basic system of Unix permissions is good for many things and a good foundation but that doesnt mean its the end all and be all of access control.