I don't get why you need a GUI for software installs? Seriously, I don't get the point of them?
Because they're discoverable. This is basically the entire point of a GUI, and one that strangely people who should know better seem to have forgotten.*
Think back to the Bad Old Days when there was no GUI. You're sat in front of a computer which has just turned on and gone "Boop" and now there's a cursor there... what to do? Well, you could try just typing random things in and hoping for the best, but that's pretty risky. Possibly you could spend a few hours trawling through the paper manual, assuming there was a paper manual.** Either way, this is pretty horrible.
With a gui you have a way of not only telling the system what you want, but you have a way for the system to tell YOU what IT has and what IT wants. This is immeasurably useful.
Now, obviously you want a good CLI too, if you're a power user or any kind of systems administrator (which I presume you personally are) because it's important to be able to make tasks repeatable and for that you need a scripting language of some kind. Bash, Powershell - I don't care which, just so long as it's there. Most people however are NOT power users or systems administrators and they not only don't _want_ a CLI, but they really shouldn't need one. If they do whoever designed the system has failed.
* See "Windows 8 and the magic disappearing tooltips" or "Ribbon interfaces for confusion and profit" to see just some ways of really cocking this up.
**You can't look it up on the internet, because it's 1984 and the internet doesn't exist yet.