Well, one problem was just that these things are cylical - space games ran their course and shooters took over. This, too, shall pass... but there were other problems regarding space sims in general and Wing Commander in particular.
The big one (in general) was joysticks.
In the early-to-mid-1990s, joysticks were common - almost standard issue (largely because of Wing Commander.) When you bought a family computer from Dell or Gateway or IBM, it came with a cheap joystick (and, more often than not, a copy of Wing Commander 2 or Privateer!) What this meant was that there was a *huge* install base for space sims... everybody who had a joystick could theoretically buy a space game and enjoy it.
Today that isn't the case. First person games took over, companies saved money by not including 'sticks... and they became a hobbyists tool. If you're one of the 11 people who buys MS Flight Sim 9.5 you can get buy an exact replica of a 737's flight yolk for $500... otherwise, they just don't exist. So when a team sits down to pitch their space game to corporate they have to explain how it will sell to 5% of the market instead of 80% and why they shouldn't be spending their time on more surefire products.
(This is, incidentally, where FreeLancers control scheme came from - Microsoft *knew* they couldn't sell the game... at the time, the most expensive ever developed... if people believed it needed a joystick. So they removed any joystick play, made a big fuss about it being mouse-only and fanned the flames to make sure potential buyers all realized that you controlled it with what God gave your computer.)
Now, add to that the general death of PC development, which has happened only recently - what was the last original AAA title you played for the PC? *Everything* that gets development money is for a console first, a handheld second, a cell phone third and a PC fourth (and maybe some kind of arcade cabinet or slot machine before that, even.) You just can't make money putting ten million dollars into developing a new PC game - except for the occasional fluke like The Sims or World of Warcraft. PC development has become very risky.
Wing Commander suffers from two other 'marketing' flaws, specific to its nature:
* Full Motion Video!... was a crazy fad that developers look back on and wince at. It was expensive, awkward and had limited expandability. Wing Commander IV cost a mint, never made it back and still looks awfully dated today. There's a perception that Wing Commander *needs* the actors in order to function... and that no one should ever put that kind of money into filming an interactive movie ever again.
* It lost its creator. There's a big perception at EA (or there was, years ago) that Wing Commander wouldn't sell without A CHRIS ROBERTS GAME on the cover. It's not true, but it's what the suits thought for years... I, personally, would be happy with A SEAN PENNEY GAME.
