The game is pretty good as it is. Certainly what you're suggesting would only increase the distance between hardcore/casual/new players. Your suggestion of increasing stats and such is basically just like leveling a character in an MMO where your demigod retains its experience outside of a single game.
The game is meant to be played like an RTS where each team starts out even steven (with the exception of Favor Items; but over a short amount of time that can even out as well; or you could even just play games without them). If you and I were to sit down to a game of Sins of a Solar Empire or Civilization IV there would be absolutely NO advantage for one player over the other except for skill and knowledge. Wouldn't matter how many times you've played a certain faction.
Some ways to improve the game in my opinion are as follows:
Get modability in place so people can go crazy with the UI and other stuff
Modify the Custom Games selection area so that games can be grouped by country/continent/region, whatever
On that note, allow for some kind of selection in the Custom Games selection screen where teams could join as a team
I should point out all 3 of those suggestions are already getting attention by Stardock/GPG so my mentioning them is nothing new. I'm looking forward to them is all.