Before you can try a demo, you need first to discover it. Today we discover games by word-of-mouth, a positive magazine review, or a passionate blog post. Later this year, we can add another method to that list: Miiverse. Miiverse will encourage discovery of software through Miis who will congregate around popular games on your Wii U home screen. Once you've taken notice of a game, the next step is finding out if that game is relevant to you. I'd argue there's no better way to see if pants fit than to try them on yourself.
One of the things I've appreciated about my Windows Phone 7 is that the majority of applications are free to try. The trials are usually limited to only the first few levels in a game or a restricted set of features in an application, but you usually get enough content to form an opinion. I hope to see Nintendo more fully embrace the increasingly-common "free to try" model with Wii U.
The obvious benefit from a hands-on experience is that I can buy with confidence. If I don't like the way the pants fit, I can throw those uncomfortable jeans back onto the fitting room floor. I don't need to spend hours reading reviews to determine if a game is something that will fit my taste and is worth my hard-earned money. I can try it and within a few minutes decide if it's worthwhile or worth deleting.
One concern I've heard from developers is that it's sometimes difficult to convey the feeling of a whole game in a short demonstration (such as RPGs or simulation games). For those instances I think the best solution is to include a video preview at the conclusion of the demo highlighting the additional content the player has to look forward to. "You like these slacks, huh? Just wait until you see me in my matching mad dog plaid dog sweater vest."
I wish I had the stats to back this up, but I think this approach ultimately benefits developers. Rather than people blindly making purchases, walking away disappointed, and having instilled in them a growing reluctance to try and buy new things, people are now willing to try anything and everything, increasing the likelihood and frequency of future purchases. Sure, it sucks for those companies who make crappy software. Now they can't fool you with a clever name or fancy logo alone. They actually have to deliver a quality package to convince you to click "buy." As it turns out, That Awesome Game isn't really that awesome. But the end result of money saved on That Awesome Game is money spent elsewhere.
Maybe that money can be spent on a game that initially just sounds plain dumb like Plants vs. Zombies. What's a dandelion got to do with the living dead? But I heard a friend mention it in passing, so I downloaded the trial... and couldn't stop playing. It's now a permanent part of my collection.
So as I sit here writing while wearing my new pair of ridiculously comfortable pants, I can only hope Nintendo delivers the full package, by both informing us about interesting games through Miiverse, and by giving us the opportunity to Try Before We Buy®.