Before I started to run a campaign with the Beta rules, I greatly considered lowering the CMB DC of 15. These forums are full of people who equally say its fine as is, versus those that say it needs to be lowered to 10 or 12. I was tempted to lower it, but since the designers seem adamant that the DC of 15 is appropriate... I ran with it.
The high CMB has really stopped a lot of attacks from various improved grab attacks that several monsters have. This was a boon to the players, however after today's little stand-off, it just seemed a little silly.
Scenario:
Our enraged Str 16 fighter wishes to bash a door down. Our Str 8 Gnome bard tries to restrain the fighter. The fighter was rolling average, however he could not defeat the DC. Everyone got a pretty good laugh out of this, as for 3 rounds straight, he could not rush his way past the gnome. Finally he gave up... probably in frustration.
I've only run 3 sessions now... and true my party consists of lower levels, however when equal levels are vying off against each other, the high DC just doesn't seem acurate.
Anyways, that's my 2 cents on this hotly debated topic.
I wonder if maybe the problem is that all combat maneuvers aren't created equal?
I have been one of the people suggesting lowering the CMB number, because I've felt that you should have probably a 50% chance on succeeding at, say, tripping someone of an equal CMB. Another player in my playtest group thought it was fine because combat maneuvers are special, flashy maneuvers with special benefits, so it makes sense that you have to be substantially better than your opponent to do them consistently.
Is the problem that we're both sort of right? Maybe you should have to be substantially better than your opponent to disarm her, but you shouldn't need to be substantially better to trip her or overrun her?
To put it another way, maybe disarming an opponent is an action that can often be "more valuable" than a simple damaging attack, but maybe that's not the case with, say, pushing your opponent back or making them prone.
In any event, I like combat maneuvers. I think they make normal combat more tactically interesting than "attack, wash, repeat," which is much more like a 4E version of combat ("use at-will power, wash, repeat"). They also let you interact more with your environment. I think PF should be in the business of encouraging their use, not discouraging it.
The fighter was rolling average
The fighter shouldn't have been rolling if the gnome was trying to restrain him. I believe that you're "doing it wrong".
I had a low-strength ranger but he had some feats for grapple. As his CMB for grappling was 5 higher than the fighters, the ranger was practically invincible in grapple.