If I have to get on a "sales call" just to see what the product is or demo it, I am not interested. Let me try it for free, and tell me what it does... I really don't have time or patience for sales calls.
At least in my company the people who have the actual budgets love sales calls. Even if the engineers tell them that the product is not good they will still buy it from a good sales rep.
For now, that's who we're looking for. And a "request a demo" is a pretty good way of finding exactly those people.