making bosses better, how could it be done?

The introduction of bosses which take only a set amount of damage like event bosses (e.g no matter the range you hit a set number based on your specfic class so dps is "balanced") would be nice, especially if teamwork and/or character control played a major factor.

Actually, I think there needs to be a new stat system. The rewards for leveling are just minimal compared to the equipment.

Imagine a new "stat" window. You get 3 points to spend per level up or something.

In said window, there are icons like skills, but with ridiculous master levels, like 100. Said "skills" are things like "+% luk" or "% boss damage" or even "+damage cap", "status resistance", "critical rate", "Critical damage", etc. Tweak them to have like +1% stat every 2 points for example, or even use them to improve skills like maple warrior, adding more stats to it (and therefore your party). The best ones get unlocked at the next job advancements, and each job has its own pool, that you can spend with points from higher jobs if you desire.

This may seem something stupid, but basically, what you have here, is narrowing the difference in damage from a player to another without relying on NX, without touching potential. Suddenly, leveling is relevant, and gives better rewards than "5 LUK, yay..." at higher levels, and leveling actually makes you more up to par with NX spenders.

Basically putting everyone on a more similar level, teamwork should be easier to achieve.