At the end of The Amazing Spider-Man, we see Dr. Curt Connors helping Spider-Man up because his web shooters broke. Why is this necessary if he still has his powers to stick to walls?
It isn't necessary... it's symbolic.
Spider-man has had his webslingers destroyed by Connors, so he only has his adhesive abilities.
In one hand he is holding the antidote, so he can't let go of that.
When the tower collapses, he is thrown violently downwards towards the building. The only way he could survive the trauma of impact is to roll, and the tower is still collapsing toward him. Rolling off the edge of the building, with no web and one hand isn't exactly ideal.
Connors grabs him to save him, by demonstrating that he has reverted to human form/found his senses. In being shown that Connors is willing to save Spider-man's life (whereas the previous scene was dedicated to the Lizard trying to Kill him), his redemption is effectively demonstrated.
Spider-man might have been able to save himself, but it doesn't matter: Curt was there to help.