Easy:
Access to VC, absolute classics from Nintendo and Sega platforms from the past, plus commodore 64 (my first system), there are so many incredible amazing games there Wii is worth buying just for VC in my opinion.
WiiWare, offers great entertaiment as good as XBLA and PSN with games such World of Goo. WiiWare + VC > XBLA + PSN in terms of offerings
Nintendo Games (they do make the best games) Zelda, Mario, Mario Kart, Metroid. Plus new ip's Fatal Frame (well kinda), Disaster etc. etc.
Other exclusives coming this year Madworld, No More Heroes 2, Conduit
JRPG's, Wii will be the dominant console in terms of JRPG's lineup this year include Fragile, Arc Rise Fantasia, Kizuna, New Tales , MH III with many more coming.
And most important new ways to enjoy your games, look at Wii Fit and possibilities that it gives playing Shaun White Snowboarding, Wii Mote + Motion Plus will do magic in sword fighting, and looking at Controls of Metroid Prime 3 shooters work extremely well on that platform.
And Even if Wii would be just your 3rd or secondary console it will offer you atlernative from HD twins, something more fresh and fun. PLus it is the ultimate party and friends system.
