I guess I'm the tool, here. I've bought a bunch, listed below. The primary advantages I get out of it are:
1. Family - My mom loves old games, but some of her favorite games' batteries are dying and she feels awkward using an emulator & PC gamepad for some reason. So for her, it's wonderful.
2. Comfort - Sure, I could go to the trouble of digging out my NES, puffing into Kirby's Adventure until it loads, cursing the heavens because my game's been erased again, or I can turn on the Wii, pull up the Kirby channel, and pick it up literally where I left off with no risk of the battery failing me. Hmm...toughy. (Also, it makes it far more likely I'll finish Ninja Gaiden again without becoming swallowed by rage since even if I die on Jaquio and quit in a huff, I only have to pick it up from 6-1 rather than 1-1 when next I turn it on.)
3. Saving me some trouble - I tried in vain some years ago to get ahold of Ys Book I & II to play on an emulator, but A, I couldn't find a complete ISO to save my life, and B, there wasn't a free TG16 emu worth beans. But they're throwing some Duo stuff up now, so once they put up Ys (and you pretty much know they will eventually), I'll be more than happy to just grab it that way (alas, not today...Lolo 2 and Super SFII instead...*sigh*).
So for a lazy guy with an innate fear of failing batteries and a family that breaks into a cold sweat when presented with a ROM menu, it's great.
This is what I currently have. I'm waiting for Ys so I can plunk down $20 and pick up it, Devil's Crush, and Ninja Gaiden 2 all at once. I might also grab SM64 once I wrap up with Galaxy. AND SOME MEGAMAN WOULD BE NICE, CAPCOM.
Breath of Fire 2
Donkey Kong Country 2: Diddy's Kong Quest
Legend of Zelda: Link to the Past
New Adventure Island
Super Mario Bros. 2
Super Mario Bros. 3
Super Mario World
Wonderboy in Monster World
Happy with most, but SF64 was a massive disappointment.