The reason why many people buy a nexus is for stock Google firmware without bloat. For me, at least, that's what I want. Also for all the fancy camera, stock firmware, world's fastest fingerprint scanner, performance smoothness under marshmallow, security, newest updates from Google directly for 2 years and also monthly security patches.
People who own Samsung, LG or Sony, they want to have a custom ROM for many reasons, mostly to have the latest version of Google Android on their phone without needing to wait for official. But on the nexus it's always bleeding edge latest version of Android, so nexus users don't have to hack in the latest version Android, it's by OTA anyway.
That's how this thread has been going too. But to each his own. I respect that.