Slightly off-topic, but I wonder why people think trip to be that much powerful tactics.
Trip isn't
that powerful a tactic, but it is very useful. As for difficulty, like anything else, it just requires a potent combination of effects to be more effective. A barbarian with 18 str, improved trip, a sweeping weapon, and in a rage (+4 str), gets +14 to his trip roll. That tips the odds high in his favor against many opponents. And while it may not work all the time, when it does, the Improved Trip feat lets you immediately make an attack at that BAB against a now prone target (AC -4). Also, unless the target has the prone fighting feat, they are -4 to making any attacks and their AC is still penalized for the AoO they draw if they try to rise.
That's pretty argumentative. It is pretty obvious that the "Improved" line of feats you mention were intended to negate the AoO that the attacks normally provoke, so it'd be a DM's call as to whether they also negate AoO's granted through non-standard means. Feat A says you don't get an AoO, Feat B says you do. It's pretty much a toss-up as to which feat's wording trumps the other.
No it's not argumentative at all. Its actually rather straightforward. Those Improved feats, as written in the PHB, specifically state that the attacker making those moves does not provoke an AoO for doing those actions. Karmic Strike may allow AoO for doing them normally, but if you have the Improved feats, then Karmic Strike doesn't work. Period. There is nothing in Karmic Strike that states it trumps Improved feats and the wording of the Improved feats explicitly negate the benefits of Karmic Strike. As for your line of reasoning being obvious, that is your interpretation and you're welcome to it, but my statement was based on the rules as written in both books. And going by the letter, and most likely the intention behind them, the Improved feats in question negate KS. There's no toss-up or anything in question.
Whoa. Major errors there. Attacks do not automatically damage either a grappled or pinned opponent. You are required to make normal attack rolls, against which the opponent receive full AC. And in fact, the rules actually state (and this is pretty dumb IMO) that while you have an opponent pinned, you actually don't have the option of attacking him with any sort of weapon unless the opponent is actually holding it for you.
Not any major errors, maybe a slip in use of automatic. But read PHB, pg 156, under the section "damage your opponent", in place of an attack, all you have to do is make a grapple check and you inflict your unarmed damage--or damage from the spikes if you're wearing spiked armor. So, in my example, with the pinned (immobile) opponent, you just need to make a grapple check (melee touch) against a target with no dex bonuses to AC, and you get your base unarmed damage + armor spikes + str + whatever. So, while automatic may have been a bad word, my point still stands that grappling (with Improved Grapple) is one of the quickest, easiest ways to overcome the KS feat.