The size of the playerbase is the biggest issue, even back in its prime, SFC was really a niche market. It hurt that networking infrastructure and technology limited it to what it was. Could you imagine what the game would be like if SFC1 was released just 4 years later?
Today's players don't really want what SFC was, it is a blessing and curse. A DD is a DD is a DD, no matter how many times you see it and fly it. That's not what the players want anymore. They want the customization, they want the ability to grow their ship as they keep playing. But most of all, they want all their work to be recognized. If someone's put 300 hours into the game, they want something for it. Not what happened at the end of every SFC game, Side A wins, Side B loses, reset the game and start again. I love that aspect of the game, as do most of the people here, but unfortunately we are a part of shrinking minority. I don't want to speak for everyone, but I'm sure that most of the people here would have jumped at the opportunity to play in a 10v10, or a 15v15 match. But instead the best we could hope for was an experimental (and very unstable) 4v4. Even the 3v3s didn't work very well if even one person wasn't on DSL or better. And in 2000-2003 most people were still on dial-up. And the problem is that that can't change without a major re-writing of the code, the network code was a product of its time, and hardcoded into it.
Its just unfortuante that we are where we are with SFC. Because I would put the depth and the immersion of SFC up against even the most popular MMOs. But the complexity of the game scares away casual gamers, and the inability to "Level" pushes away the hardcore gamers. To be frank, I don't want to simplify the game, and I don't want leveling, and that makes me a minority in the gaming community at large.