Honest question, how do you directly modify your android OS due to the source code being available?
I don't. I indirectly enjoy the benefits: I am running SOKP on my Moto G. Before that, I ran similar AOKP-based Android releases on my Nexus 4 (before its digitizer and radio went tits up.) And before that, various community releases on my Xperia Play. In every case the rewards have been many and varied. These days I run ordinary kernels (no overclocking) and try to keep things simple.
The argument was over which phone was more like its desktop counterpart. Your argument applies equally to both platforms.
Is it just "hey look I can run top" or what?
Actually having a nice userland means being able to use your phone as a troubleshooting tool. You can actually do pretty well just by installing busybox (from the app, it's free, or there's some features you don't strictly need which won't cost you very much... or do it manually) and android terminal, as well as anysoftkeyboard plus the ssh layout, which you're going to want very much. But having the option to go Wayland one day means being able to recycle the phone, use it for other purposes. My oldest phone is now a clock and occasionally plays me some MP3s. It's not really worth selling.