You can buy stranded wire in a cable form...I dont know the
designation...I just call it "cable tray wire". Its used a lot in
industrial plants where the vast majority of wiring is run in large
cable trays...the cables are then dropped off the tray at the machine
or appliance it is serving. Its probably expensive though and I dont
know what the code says about running it in concealed places...but I
know the sheath is probably just as durable as the outer sheath on
romex.

Use crimp on ring or fork terminals for stranded.

I dont have any problem with 14 gauge wire....the problem is fat lazy
americans and their power strips.....trying to run a 30 amp load on a
15 amp circuit....of course people are just ignorant...and electrical
supplies are available to anyone old enough to pick it off the shelf.