when we'll see Wedge's CGI X-Wing making a wild turn and strafing Vader's attack group. No need to include Han's character after that, so next..... oops! I'm going too far this time 
Looks that at least some of you know a bit about starfighters in Star Wars - Wedge was hit in his engines when he lost rear shields, this way he was loosing speed (even assuming that R2 units temporarily overcharged their thrusters for the purpose of trench run) and could not go on with Luke.
What is funny, though, is that he *asked* Luke for permission. Luke was also leading the 3-fighter element. I don't know much about the chain of command in that pitful rebel band
but I expected that "Red 2" (Wedge) would be the second in command after "Red Leader". Luke was "Red 5".[translation for non-geeks: Lucas' movies are messed up, as usual]
LOL, guys, c'mon: Wedge is really a cool-yet-quiet character, sort of a real hero in contrast to those who always seek the glory and fame. And he's the only thing I envy Ewan McGregor