Rear Admiral: The end is inevitable, Maverick. Your kind is headed for extinction.
Maverick: Maybe so, sir. But not today.
Bradley 'Rooster' Bradshaw: My dad believed in you. I'm not going to make the same mistake.
Amelia: Captain, still?
Maverick: Highly decorated Captain.
Maverick: He would always resent me for what I did. Why should he resent her too?
Maverick: You think up there, you're dead, believe me.
Suggested correction: The idea was to use the tomahawks to take out the airfield and prevent enemy planes from taking off. The SAMs could be evaded by flying through the canyon so the airfield was considered a higher priority target.
lionhead
While that may be so, those planes exit would have a difficult time out running and avoiding that many SAMs. It's not like the ship wouldn't have enough tomahawks to take out the SAMs as well.
Taking out the airfield was deemed necessary to complete the mission, taking out SAMs beyond the canyon was not. The original plan didn't take into account the pilots surviving the mission in the first place, so the Navy didn't bother with extra strikes on SAM sites. Maverick had to struggle to get them to approve this plan in the first place too, so he wouldn't be able to convince them to put even more effort into it.
lionhead
They still have to avoid the SAMs on the way out, no canyon to protect them then.