PCC is becoming very popular in competition, which accounts for much of its growing popularity. It is now an official Division in USPSA (alongside Limited, Open, Single Stack, etc.). Our local matches now seem to run around 20% PCC and growing every month. They are also starting to be allowed in some other disciplines.
Some handgun competitors complain about them ("shooting a 'rifle' in a pistol match"), but the appeal is there, especially when trying to make precise shots at middle distance (20-50 yards) at speed.
As someone said on an earlier thread here, you shouldn't think of a PCC as either a pistol or a rifle. It is more like a sub-machine gun that has to work within certain restrictions (semi-auto only, minimum stock and barrel length, etc.)
But competition aside, people will find lots of legit uses for them, whether for plinking or certain kinds of home defense or certain kinds of pest control.
Re: NEW: Ruger PC Carbine In 9mm (Yes, it DOES take Glock mags)
76"To initiate a war of aggression...is the supreme international crime" - Nuremberg prosecutor Robert Jackson, 1946