usually if you have a popular phone like the ones you listed there are very lightweight roms that can make even stuff phones run well
but either way yeah you're right
Huh. The phones I listed have notably tweaked roms, the only one that is running a stock experience would be the Nexus 5. EX: Htc phones have HTC sense, unless you buy the "google play" version of the device.
There is a linux kernel in development that would allow newer iterations of android to run on devices with 500 mb of ram or less, I think it might be released with android 5.0. I'm just guessing though. Then again you could always flash a custom rom onto your phone if you know what you are doing.
There's just one problem there. Who the forget uses a phone when you have a computer...
Do you even computer.