And why not? Other space flight simulators offer that as a user-interface option, for the very reason that it makes things easier in a dogfight. In TIE Fighter and X-Wing, you just need to press one key to toggle it off and on.
I have a hard time seeing how what kinds of dots you use on your radar (or whether or not you can see the cockpit) is going to make a bigger "competetive advantage" difference than the size of your graphics card or the speed of your internet connection, but nobody is proposing we lock screen resolutions or have a minimum ping... the thing is, *everything* user-configurable is arguably a balance issue. You can't lock them all down, and IMHO locking down something like the appearance of your radar is going too far.
It's one thing to be limited by your hardware and a completely different one to be forced to turn things off due to the fact you will lose a competitive edge in the game from having them turned on even though you have the power to run them. It basically forces you to drag the quality of your gaming experience down due to the actions of other players rather than what you can handle.
It also becomes yet another stupid thing for people to argue over in the lobby.
And that's before we get into the fact that making this a launcher flag now means that it increases the work for the mod involved. When it's a table setting that the mod decides to set or not then the mod decides and supports that configuration. Changing that involves a table mods and we can legitimately call it the users problem if it buggers things up. If on the other hand we make it a user's choice whether they want cockpits, radar icons or whatever then the mod has to make sure the mod still works if the user turns things off or bring back the ugly idea of mandatory launcher flags, something I spent a fair bit of time removing the -tbp and -wcs flags in order to avoid.
I'm still very much of the opinion that the mod designer should be in charge of what their game looks like. Turning off graphics so that the game will run on lower spec machines is one thing, altering the basic look and gameplay of the game by turning of elements that could be relevant to the actual gameplay of the game simply because the user wants to is another.
So if some mod out there wants to force that ugly-as-hell 3D radar on me, I'll just have to bend over and take it? 
I should point out I'm might be willing to compromise and have the table option be "Feature On", "Feature Off" or "Use whatever the user says" but if the mod designer has said that the 3D radar is integral to his plot or mod design then yes, you should clutch your heels or persuade him to change it.
Some sims do offer it as an option, but others have realized that it _does_ present a balance issue, like IL-2. IL-2 offers it as an option, but offers servers the ability to lock down that option, eliminating user control over that. _That_ would be the ideal solution, but barring that, I'm fine leaving that control fully in the mod's hands if it has been there from the start.
It would be a rather big PITA to do that. I'd have to come up with a system generic enough to handle anything people could throw at it so that they'd register all this stuff as being a user option which the server can demand is on or off. It would then need it's own options screen which would have to be kept up to date as new features were added.
What makes me unlikely to bother is the fact that even if I published detailed instructions on how everything works (as I did for the multiplayer SEXP system), only a couple of coders would bother to make sure their features actually used it.