I'm surprised the jets are not used more

[Ancient Seraph]

I think the fact that not a lot of people use jets is because they either realise it's lame, or because they play IL2 to fly the classics.
How would omitting jets be a huge mistake? A bigger mistake then leaving out the Lancaster, or Mosquito? I most certainly don't think so.
I'll explain the problem with jets. For teammates it's troublesome, because most people don't bother trying to keep up with jets (I don't, I know I can't keep up). Because of this, enemies have one 'extra' player (e.g. in 2v2 there would always be 2 enemies hanging around the teammate). So not only is it annoying for the other team, but for your own teammates as well.
For the opposite team, a jet is a random guy that buzzes in every now and then and either hits you twice on an annoying spot without killing you, forcing you to break off of your opponent, or shoots you without you standing a chance (depending on the skill level). The only way to avoid this from happening is to constantly keep an eye on the jet, which is extremely annoying when flying on someone's six.