Part of the problem is that it's all the same people participating in these games.
One thing that can help bring more new people in is to have whatever changes are necessary to make myetherwallet.com work for sending to contracts.
Once this is easier to do it will be possible for the masses to come and play these games.
This is real good point. Honestly, I have no clue why there is a technical limitation with online wallet... Do you have more insights ?