Look how you are gaining your style meter in DMC3... You are hitting a big amount of enemies at the same time with jam session. When you hit a big amount of enemies then you style meter will raise VERY fast... Also you are parrying a lot of attacks with it as well which causes the same effects. Of course there are ways to raise the meter easily but these are setups/exploits. You can't really compare that to the way you can raise it in this new game.
I actually can. Using Jam Session is technically easier since you don't even need a setup for it, all you need to do is stand near enemies.
Jam Session has a longer attack animation than Tremor, a long un-cancellable animation if you pull it off to the end, has a shorter range, needs to hit 10 times (if not more) to raise to SSS compared to two-three hits of Tremor, and the Style Meter actually drops down. Yeah, totally the same. Ever heard of context?
They both let you raise quickly the Style Meter but that's where the similarities end. People don't complain for the quick Style raise per se.