[qq]Using doublecast Ultima for 1 mp each time and Hatagea you will beat any boss in just two times running through your starting three, Including Ject. Overall you can make anyone easily invincible with all of the wepons customizing you are able to do.
[/qq]No kidding... Every game is easy if you get your characters to insanely high levels with all the most powerful abilities. However, it takes a whole lot of work to reach those abilities, they're a kind of 'bonus' for those who want to work their team up to the maximum. If you just progress through the game naturally, it's a more balanced difficulty curve.

Suppose they tried to make a game that's still hard no matter how tough your characters are... imagine how difficult it'd be to complete the game for a regular player or someone on their first time through... since a fully-maxed FFX character can deal over half a million points of damage with a single overdrive, the major enemies would need many millions of HP, and devastating attacks, in order to remain a threat. No regular character could win. That'd be pretty bad for players who don't have the time or patience to spend thirty-odd hours collecting spheres and gaining S-levels.

The FFVIII system, where enemies level up as you do, has received quite a bit of criticism, and it has loopholes, so it'd be impractical for them to use it again.

Simple fact is... if you make your characters really strong, then the fights are going to get a whole lot easier. I thought that was the point, anyway?