Dazed is a very powerful status effect, actually. It's right up there with blind and it's the low-level version of stun, which is one of the best.
Yeah, I don't see it. Dazed is nice, but it is nowhere near Blinded (-5 to hit is huge). Dazed often results in little change in the encounter. It's main advantage is Combat Advantage, not so much the lack of OAs. And if melee PCs take advantage of the Dazed NPC Combat Advantage by moving in and attacking, then they allow the Dazed foe to use most any non-Ranged attack in response.
I would rate the conditions along with how I rate them this way (for the non-obvious ones):
Dominated
Stunned / Restrained / Unconscious / Petrified
Blinded
Weakened
Immobilized (Weakened gets a slight edge over Immobilized since many foes have some type of ranged or area attacks, half damage all of the time is better than full damage most of the time and no damage some of the time)
Dazed (Immobilized gets a slight edge over Dazed. Dazed prevents OAs, gets CA, prevents flank, and is limited to one action, but Immobilizied almost always prevents a melee attack option, it's basically + 2 to hit (10% additional chance of hitting) vs. the much more than 10% of foes that cannot attack at all or are limited to a weaker non-melee attack, these are close though)
Prone (Dazed has no OA and gives CA all of the time, Prone has an extra minor and gives CA some of the time, so Dazed wins out)
Marked (Prone almost always forces a Move to stand, so Prone typically has one fewer action and limited mobility, the CA for some attacks with Prone is a wash with the penalty to hit for some attacks with Marked)
Slowed (the limited move for Slowed rarely does anything, but the target selection of Marked is controlling)
Deafened