Why is installing a different OS/Custom Rom on phones a huge hassle?
Unlock bootloader (depending on vendor, you have to do an online verification),
flash a recovery.img,
load into recovery mode (which, depending on the phone, might need extra work)
wipe some caches,
select new os/rom image,
pray it doesn't brick your phone.
You'd think someone would've learned a thing or two from the easy graphical installations linux and even windows have been offering since the late 2000s.