I agree. If not for the dev, they should do it for the sake of the user experience. A "Try It Out" option would prevent customers from feeling duped when they buy an App that they think looks good but turns out to not be of their liking. Which right now contributes to the customer to be more hesitant of purchasing the next app tomorrow.
What's happened in practice is that the market is moving towards free apps + IAP to make money. I think this tends to ruin most games but for a lot of other categories I don't think it's a bad model.
As a consumer, I like this model when it's done right. I like being able to "test drive" an application and then paying for the app.
For example with a business app like Grafio, I want to test drive it to see if it works for me. Then I can pay a significant price for the app - if I am using it in a business setting my time is worth hundreds of dollars per hour and the prices of apps are not really a significant expense.
I would want development of Grafio to extend further towards supporting my business needs, which is Visio import/export, and I would gladly pay for that feature.
I dislike when the free app is missing important functionality (this defeats the test drive aspect) and I dislike when the in-app is a subscription.
I find it obnoxious when apps have too many in-app purchases. It becomes an annoyance to have to pay $1 to read, $1 to write, $1 to save. Just ask $3 for "full functionality" from the start. Don't be silly.
I like when the app is fully functional and I can choose to pay different amounts to support further development.
As a developer, I also prefer to have test drive option. Some apps can't be test drive (for example, casual games), but for productivity apps, it is a must have feature and windows phone has it from day 1.
