If you've gone 10:1 on infantry only maps it means you're a legit good player or just sniping from afar. Is that realistic? As far as a game goes, sure.
Your last two sentences here aren't really keeping the nature of the game in mind though. In real life, we're not carrying GtA missles that much because the persistent air threat just doesn't justify having them. In real life, if there were as many persistent air threats as in game, you can bet we'd have a lot more anti-air resources.
In the game, unless they're going to make air vehicles spawn only at certain times, this isn't going to be the case. You destroy a F/A-18, another one pops up at the US base very quickly. That F/A-18 isn't 40 minutes away, it's 10 seconds away. Thus the in game levels of GtA should be inflated.