I believe I have determined why area effect powers are so tempting to take when designing characters. I've noticed, for instance, that is extremely hard to resist "divine glow" when making a cleric, it just looks very effective.
It appears that character powers are designed using a rigid set of guidelines, similar to the way that monsters are built in a somewhat mechanistic fashion. A level 3 encounter powered as a base 2 dice of damage. If the power has a strong advantage, such as area effect or an evil special effect such as dazed, the power is reduced to one die of damage. That's it, except that I think the kinds of special effects allowed becomes more broad at high levels (you never see stunned at low level).
Therefore, divine glow could have a 2d8 ranged power instead of a 1d8 close burst 3 enemies only power. When you factor in damage bonuses, this means that a ranged power only does 50% more damage than an area effect power like divine glow (and probably doesn't increase the special effect at all). It is, of course, extremely difficult to compute how much better an area effect attack is, since it depends so much on the style of fights and monsters you encounter. But close burst 3 enemies only is surely more than 50% better than a single target ranged attack (probably it is at least twice as good). Explaining why divine glow seems so tempting.
This also explains why blinding barrage is so insanely potent. The rule for a level 1 daily power seems to be that it does 3 dice of damage, reduced to 2 dice for powers with strong benefits. Since blinding barrage has strong benefits, it does 2 dice of damage. The fact that the power has 2 great benefits, and is in fact obviously quite mighty, doesn't factor in. The only mystery here is why they allowed this type of power as a level 1 rogue power at all. A area effect attack with a vicious control effect would seem like something that only a controller class would be allowed to have.