If you only charge $1 for your app you’re missing out on everyone who would download it for free. Sometimes you want to use money as a qualifier for something, but it depends on the intentions of the application, its value proposition, and target market. If you’re operating in a self serve model and the goal is to get as many customers as possible, a free limited version will drive more conversions to Pro if your Pro offering has enough added value.
Not to mention, most people want to try things before they buy them.
Using money as a qualifier is fine, but it will limit your reach and change your marketing plan. Free trials enable you to learn from your customers, and build better products that convert to paying customers.