I wouldn't say teams have gone backwards, its just the superpowers in the game are improving faster than the minnows.
A lot of the new ideas in coaching and training techniques have not been passed down to the minnows. Thats why there is a noticeable disparity between the top sides.
So really for the minnows to get better, we need the superpowers in the game to start helping out. If anyone has seen Japan play this tournament they have actually been very good in attack, the best that I have ever seen of them. Reason for this, Mark Ella is their backs coach. His experience has proven a winner for the Japanese side. All is needed is for more "Mark Ellas" to go out there and help the Georgians, Uruguayans etc.
I'm sure the IRB are looking at the tournament now and thinking that the highscores are unacceptable and something needs to be done before the next world cup arrives.