I Can't Go Back
In the 80's I used to play Diplomacy by mail. Remember the mail? You put stuff in an envelope, write an address and a return address, put on a stamp, drop it in a box, and wait. And wait. The average turn length was one month. It was almost intolerable even then.
Of course, this was long before the Internet existed for me. It wasn't until around 1992 that I learned about Prodigy and Delphi. These were closed dialup systems where people could hang out, chat, and play some simple text games.
About a year later, I got my first real Internet access at home. $20 a month for "unlimited" access at 33K baud. Browsers were crap, but so were the web sites.
With everyone now interconnected, it's easy to play any game you want. But even in the last two years, I find technology pushing me forward, making it difficult to use what had been good enough not too long ago.
Most games are now graphical. One type of system allows you to make your moves, save the game, and email the game state to your opponent. In their own time, they do the same.
Play-by-web has eliminated the burden of sending the save file to your opponent(s). Simply take your turn and click DONE. The next player is emailed indicating that it is his/her turn.
Play by email/web games have one huge disadvantage. They only work well for games with little or no interaction during a turn.
Now enter live gaming. Players all connect to the same server at the same time, and play out their moves as if they are sitting at the same table. You can even text chat with each other. Still not as good as face-to-face, but better than playing nothing.
The real social element comes when you add voice to live gaming. You can easily teach games, and you can chat while playing. You can even play play-by-web games using voice. The experience is so much better than anything else short of face-to-face, that it's becoming difficult for me to play any other way.
You want to play something on Vassal? Sure, but do you have Skype? Skype is free and so easy to use that you are going to have a tough time getting me to play something without it. The only exception would be if all the players could not be on at the same time.
What's next? I doubt that video will fill a technical void like audio did, unless you take it far enough that you wear 3d goggles and see all your opponents sitting around a virtual table.
I really think audio is good enough. Now it's time for games to get better interfaces, and for more good games to be implemented for online play.
I would never play anything by mail any more, and it would take a miracle to get me to play by email. If you haven't done so, I urge you to try live/web gaming using Skype. Give me a poke on BGG. We can play something, or one of us can teach the other a new game. You too will have a hard time going back.