Just as you don't understand fork and spawn, you clearly don't understand how privilege segmenting works in Linux. Much of the kernel runs in Ring 0 for example. It can disable interrupts and do all kinds of things that systemd cannot because ... wait for it ... it runs in user space.

Since we're talking about LInux don't you mean clone ?

Every distro has it's package manager and with it different syntax. Imaging if you had a tool like "install-it mysql" which on Ubuntu goes to apt-get install, or pacman's syntax, or yum or whatever.

Has been tried before https://en.wikipedia.org/wiki/... by many systems.
The problem as I see it is that Linux software ecosystem is chaos. There's a lot of movement which breaks stuff regularly

The thing I mostly worry about is packages. Say what you will about Windows and Mac, but developing an app for them generally has a limited set of ways. There is only one way to do services in Windows, etc.

That's not really true. You can start services/daemons as a service* (under svchost or on its own), as a logon batch job, via a user's startup folder, on demand, ...
Windows has had its fair set of installers as well: Installshield, nullsoft, Macrovision, ...

It is hard to get say Webcam apps to get ported to Linux because the poor devs have to figure out webcams in 10 different distros. Everyone in the boards say "ubuntu 14 +1", .... no no Arch first!!! and so on. Should it matter as much app to app? Shouldn't distros at least have some level of uniformity...a layer of it.

Just use the proper kernel subsystems and sysfs.

I know they sell cases where the PSU's are at the bottom. It's a gimmick to sell cases to people that think that's a better design. It's not. The one and only benifit is the weight of the case is now at the bottom and it's less likely to tip. But heat wise, the PSU is the biggest offender in your case. It's also one of the most heat tolerant components. A good, basic, design has large fans in the PSU pulling air IN from the case and exiting the PSU out. All other fans are blowing IN to the case so all airflow enters the case first, travels through and then exits the PSU.

No it's not. The GFX card and the CPU are the most heat generating components.
The way it works nowadays is that the PSU draws air from the bottom circulates it over its components and pushes it out the back out of the case.
That air is not gonna to be drawn back in.