If I dont feel the bass....then its worthless. pa's are okay, but most the time you have to be on top of the damned monitor to feel the bass. Oh sure maybe you can hear it, but I mean feel what the heck youre playing. I dont care how many class d watts will go into a 112 combo or "mini stack". I have to feel it. And it has to EASILY compete with 2 50 watt fenders, and a loud drummer.
You may not have experienced this, but putting 300 to 600 watts into a pair of 12's is PLENTY capable of making you feel the bass. The last gig I played, a single 12 had the stage flexing so I could feel it with my feet as well as my body.
It does not take a stack of 15s to move air and feel the bass. And I play with two guitarists using 60W Fenders and a surf drummer who's like a machine gun. Then again, we don't play at 120dB and cause small birds to fall from the sky.
And we don't even use a PA except for between-song announcements.
Using a modular system also makes load-in and load-out much faster and more pleasant, and makes it possible for me to travel to the gig in a smaller vehicle.