With Samsung's android record, why would anyone want more Samsung written code on their phone? I had a nexus 5, reliable, reasonably fast, snappy under most no

With Samsung's android record, why would anyone want more Samsung written code on their phone? I had a nexus 5, reliable, reasonably fast, snappy under most normal usage patterns. I wanted a SD card and wireless charging so I upgraded to a note 4. 50% more ram, faster cpu, faster GPU etc. Felt way slower, and crashed fairly often. Annoyingly the home button was quite sluggish. Even more annoying is despite 50% more ram it was very aggressive in killing background apps, making multitasking almost useless. So whenever you switched apps it would have to restart the app, MUCH more so than my nexus 5. I tracked it down and apparently it's some benchmark optimization. Android updates (security or otherwise) were quite rare and was about a year behind on the android releases. I switched the note 4 to cyanogen. The phone was much snappier, much more consistent (no random lag), and stopped crashing. Oh and the home button was much quicker as well.