I like doing the Uprisings and tactical FPs solo- I've found that different companions work better for different bosses, and there's a learning curve in companion management- setting them to passive at the right time to get them to move out of fire, etc.
To respond to the OP: I like the idea. I've always thought having a "Mercenary" system, where you could fill open (or all) other slots with something similar to the Combat Droid to run a FP or Uprisings, without nerfing the content like the Story Mode stuff. For instance, a Mercneary Guild NPC would be available on fleet that sells tokens you could pop inside an instance that would spawn a healing droid, DPS droid, whatever...to fill holes or let you run it alone.
I would still be good with XP accruals being scaled (i.e. "real people" groups should get the grouping bonus, droid groups wouldn't, or it would be scaled back depending how many 'real' players were in the instance), but it would be cool to be able to run (more) content solo.
My 2...