dtgreene: 3. The game has lots of high-level content, but the game is not balanced at high levels. In particular, any attack that isn't Quick Hit with a Celestial Weapon (those ultimate weapons that require mini-games) fails to have any strategic use at that point, as physical attacks scale faster than offensive magic. Furthermore, even if an enemy has high defense, Celestial Weapons ignore it, making offensive magic use not even have that possible niche.
a4plz: Very knowledgeable analysis. FFX was one of the first games that got me thinking about proper handling of end-game content, because it could've been improved in so many ways that the developers were seemingly oblivious to.
I could point out that it is still quite difficult to balance RPG systems at high levels. Consider the Disgaea series; the post-game isn't always the most balanced. (Disgaea 3 and 4, to my understanding, were especially bad; the game would reach the point where every hit is a one-hit kill, making HP and DEF useless.) Or take D&D 3e with the Epic Level Handbook: balance breaks down to the point where people don't actually play at those levels that much, and by the time you reach level 100, there's pretty much no balance left. (I mentioned in another thread that, at level 4000, a 1% level difference can mean the difference between almost always and almost never hitting. Disgaea is fortunately not *that* bad.)
Going back to FFX, one other issue is that, by the time you reach post-game, bosses (which are the entirity of the post-game content) are immune to pretty much everything they can be immune to. This makes entire categories of abilities (such as status effects) entirely useless. I want spells like Sleep and Death to be useful.
Another issue with the FFX post-game is that it's all bosses. There are many interesting possibilities with dungeon/random encounter design that are basically unused because there are no dungeons that are intended to be a challenge to characters with 3-digit stats and 5-digit HP. (Speaking of which, the damage limit seems rather arbitrary, and I don't like the fact that one specific ability (Break Damage Limit) becomes mandatory at high levels.)
By the way, is there a video of Penance being defeated without celestial weapons? How about one that uses only magic? (Of note, I prefer videos where Break HP limit is used to those where it isn't; I find it more interesting from a health management perspective.)