Because SE hates you. That simple.

Seriously though, you're not wrong. Clemency isn't unusable or anything. It's great for AoE dmg, but not as useful as it could be. AT THE VERY LEAST, they should give Pld's a way of sure-casting it (Additional effect of Tempered Will. You know, that move that Pld's never use and often forget they even have... Just a thought).

Stance dancing should also be adjusted, if only for the current Dps meta. Right now, anytime a Pld has to contribute to a Dps check (say...Sacred Cross... or even the Sword Oath Knight in Thor EX) they are made even less effective because of combo canceling. Swapping to Sword Oath wastes precious time, and not being able to swap back on the fly (because no Pld in their right mind wants to be in SwO when a buffed Holy Blade dance goes off) restricts them to basically clenching their butt cheeks and hoping for the best.