Heat can be dealt with better, but it will come at the tradeoffs of thickness and weight. No one wants to carry around a 10 lb laptop plus a big ass power brick. There would probably be more fans spinning at higher speeds, further decreasing battery life.
Not with it, IMO.
Repasting the heat sinks with better thermal grease and the use of external platform fans would probably help more at a lower price without adding bulk to the laptop.
Agreed, leave them all on. It’s not like they suck much resources, and why potentially introduce problems for minimal, if any, gain?