As I recall, the DPS "hierarchy" went something like:
- Rogues
- Wizards
- Monks
- Mages
- etc.
Every class has a mix/balance of: (generalizing)
Tanking Ability
- Damage Mitigation
- Disciplines
- Disarm
- Absorption (Spells)
- Etc.
- Damage Avoidance
- Armor Limitations
- Skill Limitations/Caps
- Threat
- Etc.
Healing Ability
- Healing Skills/Spells
- Direct Heals
- Heal of Time
- Mend
- Etc.
- Buffs
- HP Buffs
- AC Buffs
- Stat Buffs
- Resist Buffs
- Etc.
- Resurrection
- Resurrection Spells
- Convergence
- Bind Wound
- Etc.
Damage (DPS)
- Equipment Limitations
- Crits
- Skills
- Kick
- Bash
- Flying Kick
- Backstab
- Etc.
- Spells
- Direct Damage
- Damage Over Time
- Damage Shields
- Area Effect
- Self-Based Diameter ("Point-Blank")
- Target-Based Diameter
- Etc.
- Skill Limitations/Caps
- Etc.
Utility
- Movement Impairment
- Movement Increasement
- Gate
- Teleportation
- Buffs
- Spirit of the Wolf
- Spirit of Scale
- Wolf Form
- Etc.
- Levitate
- Invisibility
- Regular
- Undead
- Animals
- Hide
- Sneak
- Pets
- Etc.
Certainly the "Utility" list(s) can go on for quite a while. The point is -- Every class has a balance of Tanking, Healing, Damage and Utility that defines what roles they can perform and how well they can perform them.
Rogues are top DPS because they have very low Tanking ability, virtually no Healing ability and very low Utility. This "frees up", if you will, theoretical "points" that then get spent in the Damage department.
Wizards have their own checks and balances. Certainly the limitation of Mana is one to consider, but that has its own pros and cons associated with it. Wizards do the most "Burst" DPS of casters (possibly all classes in regular case scenarios?), but also have the best mana:damage efficiency of all casters. I believe wizard nukes are an average of 10% more efficient than a mage's nukes.
The territory also comes with additional utility like Invis, Group Teleports and Root, as well as some baked in resist modifiers that make some spells have an easier time passing resist checks.
I am not a wizard, nor have I played one, but I've never seen anything necessarily "wrong" with them. Every class just offers a flavor certain people find more desirable than others. Utility wise, Wizards are a little "bland" with the exception of Group Teleports, but the real strength of a wizard is on the back end of the mechanics anyhow.
All in all, I'd say Wizards are a pretty good class. The only class, I feel anyways, that is deserving of pity is the Ranger, whom saw their "fix" really come in during Luclin when they got AA's to bolster their previously "inadequate" Bow DPS.
Possibly Paladins as well, since their mitigation deficiency compared to a Warrior wasn't quite made up for through their defensive/healing twist on the class. Whereas a Shadowknight got more DPS for their reduction in Tanking ability (which was always useful), Paladins never really assumed a healing role and the group still required a dedicated Priest class for healing. On the other hand, Knight aggro was pretty fast and pretty snap... so they did make really good tanks for exp groups...
(I concede I'm really caffeinated right now and borderline rambling too much, so I'll shut up now)