The point I'm trying to make is that I feel it's something of a mistake to start from the position of: "Ability X is less powerful than an optimal spellcaster, so therefore it is not in need of balancing or power reduction", in part because the optimal spellcaster is something of a theoretical creature, and in part because it seems reductionist to say that this is always the case.
In the case of pouncing, a well-designed pouncer (in a decent support environment especially, such as one that includes a Bard (even a non-DFI bard)) can deal enough damage each round to pretty much kill one monster at CL+1 or CL+2 per round. Five or six attacks, each of which has 5d6 precision damage, is enough overkill that it sort of moots the question. If spellcasting is "better", both scenarios end up with killing the monster, and the pouncer can do it more often.
I think that when we compare to spellcasters, we often forget the limited uses per day of most of their signature moves, which can be a powerful limiting factor (although, again - it's asking the DM to intervene in the balance equation, which can be problematic).