I got to thinking. . .why is it that hardly anyone uses Dispel Magic? So, I delved into how it works, and realized something:
Dispel Magic, as it is in the game now, is **** for players and massively powerful for Monsters. Why? Let's look at how it actually works.
Let's say you have two spellcasting creatures, one is the Player, the other is the Monster. Both have a number of buffs active, cast by themselves, and know all 3 of the main dispel magics: Lesser Dispel Magic, Dispel Magic, and Greater Dispel Magic. Both have 14 caster levels. This is important.
Player casts Lesser Dispel on the Monster. The Player must now make a caster level check against each ongoing buff that the Monster has. However, since the Player is casting Lesser Dispel, the level bonus is capped at +5. The DC that must be made is equal to 11 + Spellcasting Level (14 in this case). That makes for a 1d20+5 roll VS a DC of 25. Notice that this means that Lesser Dispel is worthless in this case: a mere 5% chance for each buff to be dispelled.
Dispel Magic is a bit better, since its max caster level bonus is +10. Greater Dispel Magic is of course, the best, with a max caster level bonus of +20, and as such you'd get the full +14 bonus, which gives a 50% chance of debuffing each spell effect.
Now, at this point, the system works fine. People could actually use this to reasonable effect. Where it goes screw-eyed is when you enter Hard or Elite difficulty. In those, it's more than likely to encounter monsters with a Caster Level of 20. Suddenly, the chance of any dispel that you cast of working becomes rather worthless in the eyes of most players: 20% chance for each buff! And that's with Greater Dispel Magic. The lower versions won't even have any chance. Ever get hit by a nasty debuff that you try and dispel on Elite difficulty? Good luck. . .you'll need it.
Conversely, the Monsters can cast dispel magic spells with wild abandon. . .d20+20 vs our DC max of 25? Child's play for them to dispel. In all likelyhood it'll only get worse as quests get higher in level.
How to fix it? I'm not sure.