Ditto what others have said: in the right set of circumstances, these tricks can be very useful.
Our group was recently in a big fight with a BBEG godlike melee monster, and both grapple and bull rush factored significantly.
The BBEG was hitting regularly with 3 of his 4 iterative attacks, and doing over 30 points on most hits. Plus DR that not all of us could beat, and regeneration. And a decent AC and monstrous SR. Plus surrounded by countless minions, ranging from Ogres to advanced Fire Giants with class levels. Our plan was to teleport in, do as much damage as we could in the short time before we started getting our butts handed to us, then TP away. We had disregarded a bunch of dominated centaur mooks, until in the 1st round one of them (familiar with our hit-and-run tactics) decided to charge into the middle of the party, heedless of AoOs, and bull rushed our cleric out from under us. All of a suden, we couldn't teleport away as a group (have to be touching), and our healer was gone. Then the BBEG teleported into the space the cleric was standing in a moment before, and handed us a whole dumpster fulla' whoop-arse.
We had done some damage, but even with battlefield-control spells keeping the mooks away we woud have been dead meat soon, except I managed to get a Dimensional Anchor spell to stick on him. Next round, I Summoned 3 Huge Fiendish Consrictors to try and Grapple him. Our spells were boucing off, but I figured you don't get spell resistance against a grapple, and pinned is as good as Held, at the end of the day. One snake succeeded, and I knew it wouldn't take long for the Beast to break out of the grapple, but that was a few rounds that he wasn't wailing on us. In those few rounds, we took him down. Our DM did NOT expect us to be able to do that.
So, on one hand, a well-placed bull-rush really ruined our day. On the other hand, a well-placed grapple saved our butts.