Using dice sites with bitcoins wagered stats is misleading.
Because eventually, the bitcoins wagered will exceed the maximum amount of bitcoins in existence.
Wagered actually means what was bet, and the coins are reusable. If I bet and win, and I bet again, it's the same coins being bet. If I bet and lose, and I bet again, then maybe that is more accurate.
But people do not lose all the time. They lose depending on the percentage chance to win.
Also, JD is off-chain, meaning all action is internal. You don't see any action on the blockchain unlike SD where everything is in the blockchain. But people don't like that either because it's polluting or bloating or spam.
You only see deposits and withdrawals, and since it uses bitcoind which generates new addresses all the time, we can miss out on much of the transactions.
The only thing we can see for sure are the JD cold storage and online storage and part of the hot wallet.
I am not sure just because the transactions occur off-block chain that it makes them any less significant. True you do not see all the dust spam like with on-block transactions by entities such as SatoshiDice, but the coins transfer you see in and out are quite large my quantity.
It seems that online gambling has been a hit for bitcoin, but this may not be a good thing due to bad publicity for policy makers. I suspect the psuedoanonymity also will work out well for porn sites who will start adopting it with time. Noone wants that foot-fetish site to show up on the family credit card statement. But I suppose, porn and gsmbling and the vices are always the innovators. I remember pay-per-view and DVDs got big with porn well before mainstream media.