Back in the original PnP D&D 3.5, Dispel Magic is separated into three spells, that were not game-translated when converted to DDO: 3rd level Dispel Magic (caps at CL 10), 6th level Greater Dispel Magic (caps at 20), and Mordenkainen's Disjunction (no cap).
However, back in PnP most mobs DO NOT have caster level equal their CR. An ogre with mage levels have a very low CL. Even player classes as paladins and rangers only have caster level equal to half their class levels. And that is not counting the prestige classes that do not improve casting at all.
In DDO, however, every casting class level gives you +1 caster level. Every mob able to cast spells have caster level equal their CR. When faced with the fact that hard and elite mobs (and normal bosses) have caster levels above your own level, you notice that the Dispel Magic mechanic ends with you having no chance to dispel any effect the mobs cast. Add to this the second fact that the devs decided to buff monster directly on their bare stats instead of many layers of buffs that, if not being able to be removed, at least suppressed for a time. This lead to Dispel Magic being pretty much useless in DDO.
They tried to give us a reason to carry Dispel by making it de-level Spell Wards, but it only appear in Forgotten Realms content, that is all level 16+, requiring you about a dozen casts to remove a single spell ward. And since you usually do not backtrack on those quests, and you have to face-find the spellwards if you don't have trap skills, it is usually more efficient to just run through them. Again, Dispel stay useless.
And to add insult to the injury, with U19's enhancement pass, they gave Arcane Archers the possibility to instantly dispel up to three effects from any mobs a Dispelling Arrow hit, regardless of buff level. So, let me clear this point: A 3rd level ranger (that i PnP only have half their levels in caster level) is a better dispeller than a 30th level full-caster.
I propose the devs to change the way Dispel Magic and its enhanced versions works to the following:
Dispel Magic: Dispel a single effect on the target. This might dispel anything, beneficial or not, but only one effect (randomly chosen). When used against a Spell Ward, it have 1% chance per caster level to immediately destroy it. If that chance fail, the spell ward loses 1d4 levels.
Greater Dispel Magic: Dispel all magic effects on the target. This includes any magic effect, beneficial or not. When used against a Spell Ward, it have 5% chance per caster level to immediately destroy it. If that chance fail, the spell ward loses 2d4 levels.
Mordenkainen's Disjunction: Dispel all beneficial magic effects on the target. This do not remove any effects that is prejudicial to the opponent. The target also have to make a Will save, or be unable to cast for 20 seconds (Red-named immune to this secondary effect). When used against a Spell Ward, it immediately destroy it.
Break Enchantment is not altered by this proposition because it already have its uses to clear out area spells like clouds and blade barrier.
For reference, Dispel Magic scrolls/wands have CL 5 (5% chance to destroy wards), and Greater Dispel scrolls have CL 11 (55% to destroy wards). Since both spells will also remove prejudicial effects from target (ie, dots, CC, charms...), it will not be overpowered to have scroll stashes of them, but will be an option on some fights.
Dispel Magic only removing one effect will also help against the few mobs that love to spam this spell. Sure, it will remove one of your buffs anyway, but will not clear ALL of them, like they currently do. You can also make strategic use of lower buffs (just to raise the sheer number of buffs you possess) to prevent dispelling of essential buffs.
Disjunction being the selective effect also gives us another level 9 good option, since it will also combine some strategic uses when we can nullifies an annoying caster for a while.