[Taxacom] Usefulness vs. convenience (Protista)

[Kleo Pullin]

I have a few questions about this discussion:
 
1. Why/how/for what is Protista more useful or convenient?
 
2. And what is the difference between usefulness and convenience--this thread is titled "Usefulness vs. convenience?"

>>        As for rhodophytes (and glaucophytes),
Cavalier-Smith includes them in a very broad Kingdom Plantae. Others
have left them in Protista, but included green algae in Plantae (making
it equivalent to Viridiplantae). 
 
3. Who has left rhodophyta in the Protista?
 
 
Thanks,
 
Kleo Pullin