Custom roms are good but not really a must have. It offers a variety of tweaks and stuffs but as mentioned, the build will stabilized over time. But for some phones, its a pain not to have enough available custom apps/roms to play with. Now, i just root the phone, remove bloatwares, insatall xposed framework and just get the modules that works for my stock rom.
Sent from my [Root] O+ 8.15, Stock Rom using Tapa Talk