Well, he DOES appear, you know... in fact, the Touma appearances in Railgun are among the very best parts ^_^
Think about his first faked "pseudo-loss" against Mikoto, which made her extra mad, causing her to chase him around the whole night.
Think about his interference with the thugs, while she was about to find out about the source of the level-upper.
Think about his running into Mikoto checking out an embarrassing pajama, and the fact that he managed to protect the mall visitors where she herself failed.
And and and. He DOES appear multiple times already
