perhaps he's not trying to lure ichigo and co, but luring the more troublesome captains?
I mean byakuya with his bankai can make an attack that will hit everyone, it may not hurt them much given how powerful some of them are, but it may be enough to give the other captains an opening.
Kenpachi is well... kenpachi, he's a crazy bastard, and no matter how strong aizen is, I doubt he wants to fight a wild unpredictable person like kenpachi.
Mayuri, the sick scientist with the poisonous bankai. All mayuri has to do is spread his poison and aizen's followers would if not die at least be incapacitated for some time.
The way I see it, he led ichigo and co to HM to draw the most troublesome captains there so that when he attacks, he'll only have to fight the captains that are easier to handle.
Soifon? probably not an insect, but she doesn't have any abilities that would give him trouble. Sure she only needs to hit twice in the same spot to instantly kill, but if she can't actually hit him with it, it doesn't pose a problem. I mean, based on what we've seen Aizen is incredibly fast, that or he uses his shikai to trick people into seeing him in one place when he's actually not there, either way he should be able to avoid her attacks without too much trouble.
Kyouraku? Seems strong, but he doesn't seem like the type to have overly wonderful or unfair special abilities.
Ukitake? same here, plus he's sickly.
Yama? definitely strong, but once again, doesn't seem like the type with special abilities. And then there's the fact that his power seems to hurt people around him indiscriminately, so if he went full on he might hurt more of the SS people than Aizen's people.