While I have personally wanted demo's since the GameCube I don't think it would solve third parties problems. Would demo's increase sales? Yes and no. Titles like RedSteel2 and MonsterHunter might see improvement due to the quality of the software but titles like MadWorld would loose massive amounts of sales who would buy that crap after playing a demo?
In the end I would love to see demo's it would force third parties to make better software for the Wii. But I doubt Nintendo will give us demo's I think the Wiiware ones were released due to a lack of sales and Nintendo wanting to promote its online network! Nintendo doesn't believe in demo's unfortunetly.
-JC7
"In God We Trust - In Games We Play " - Joel Reimer