Really? No one makes them? That's why DCS still has their series going, and IL-2 just came out with the Cliffs of Dover a year or so ago?
Yeah, it's a niche market, but so what? Not everyone wants the latest CoD shoveled down their throat, or some oversimplified "plane fly and shoot missiles pow pow!" 12-year-old approved bilge.
That's why these types of games will always have smaller, but fiercely loyal fanbases. We see it with Paradox and other deep strategy games, we see it with flight sims, etc. So, yeah, some people actually DO appreciate some depth in their games outside of "Press X Button to Win Game"