I think the fundamental difference here is that DLPB is grinding a lot more than Mako. FFX is a game which is fairly hard if you don't grind, but ridiculously easy if you grind that much. What's more, grinding isn't difficult, just boring and tedious. A typical player will not grind that much. When I play RPGs, for example, I always fight every enemy in my way unless I'm really low on health and in a hurry to get to the next inn/Pokémon center/magical healing cutscene, but I virtually never go out of my way to FIND additional enemies for experience unless I find myself underpowered and unable to continue at my current strength.
The problem is that too many RPGs, FFX included, essentially treat grinding as a time-consuming cheat code. All you have to do is the same damn thing repeatedly for twelve hours straight to be essentially invincible. It's not tough at all, except on the attention span, and the only real challenge to the game is one of patience. If a player is more focused on the story and wants to get quickly to what happens next, he likely WILL find himself having more trouble as a result.
One game that surprised me and got this aspect astonishingly correct is Pokémon Black/White. Yeah, the games are way on the easy side, but they also severely gimped grinding, by not only increasing the amount of experience needed at higher levels, but reducing the experience gained for battles where the player has a level advantage. When grinding is giving ~1exp per battle, the player pretty much has no choice but to advance the story and continue to an area with more difficult battles, rather than grinding forever and having an army of Lv100's before the game's halfway point.
I'd love to see other, more difficult games take this stance on grinding. It probably won't happen, but I'd love to see it.
