Destil
Explorer
Let's not get too warm and fuzzy here. This is the internet. When one person proclaims something adamantly, a score of people feel compelled to rush forth and denounce it with equal resolution.
There are some pretty blatant power discrepancies in 4e. Most obvious is that any class that has to use implements is going to pack less of a punch than a class that gets to use [W] attacks, and they're not compensated in any kind of quantifiable way. Most heavily impacted by that discrepancy are strikers, since it's the most damage-centric class. That leaves warlocks and sorcerers warranting examination. Sorcerers can focus on multi-target damage than any other striker currently, so they have a niche. Warlocks are, however, among the most single-target-oriented, and their damage is sub-par. This creates a valid argument for deeming them inadequate at their role.
Strikers aren't 100% damage and nothing else. They elimiate targets, they're not DPS and this isn't WoW. Warlocks have lots of interesting abilities and can be terribly durable and slippery. Like wizard there's a bit more bleed from their secondary role, but they're still generally useful.
There's more to each class than idealized DPR numbers.
I agree entirely on weapon/impelement disparity, but warlocks can just use pact blades and weapon feats to get around it, if that's what you really care about.