Probably because they're kind of hard to get right - It's too easy to make it too 'realistic,' which is both a problem from a controller perspective and where it falls on the 'casual to hard core' scale, or to make it too simplistic, at which point it's just boring.
We're currently at the forefront of it coming back or dying forever, though. Star Fox Zero was released today (I'll tell you how that goes later tonight after it's delivered), which is of the simpler, more console friendly variety, while Elite Dangerous and Star Citizen (And several others I can't recall at the moment) are working on the more complicated, PC friendly side of things. Elite Dangerous has proven that can still be popular, and Star Citizen has proved it can be a monstrous financial success - They just have to deliver the final product without tripping over themselves and the flood gates may very well swing wide open.
Hero of Lime said:
You would think now would be a perfect time for there to be another mainly star fighter focused game made, what with all the Star Wars love going around. But then I remembered, EA has the rights to all Star Wars games for a while. Maybe it's for the best that they don't return yet.
Yah... while I can't prove it, my sneaking suspicion is that EA is sitting on Rogue Squadron, along with several other potential Star Wars concepts/properties, to keep people focused on the DLC train that is Battlefront.
Perhaps when that game starts to have diminishing returns on profit, they'll begrudgingly give us the Rogue Squandron we're all chomping on the bit for.
EDIT: Star Fox get. Whee!