Consider two scenarios...
One, suppose a paying customer decides to buy something, then finds they don't like it, and wants to return it? In that case, the vendor incurs a cost for dealing with the return, which will mean no ultimate income from the sale. Whereas, a free download to try something and discard it, costs nothing to either side.
Two, suppose the downloaders really like what they see, and share it with friends? And the friends, in turn, share with friends. The item may eventually reach several people who are more than willing to actually buy the product (if it's good). The paradox is that the act of preventing a single "illegitimate" download was blocking many more legitimate sales.
Both of these scenarios highlight perhaps the one thing that vendors are refusing to admit, which is that quality matters most. Anything that is inherently good should have no problem making money even if it's pirated. Their beef might be that they can no longer push crap on the public and make money based on the shininess of their packaging.
Is it right that I have to wait an entire year to see the movie on DVD, when they know full well from before production starts that it will be released on DVD. It's just a tactic to try and force people into the cinema: "You like the look of this movie... ooh, only in cinema!"
With the amount of Cam rips and TS's out there, and have been out there for a long time, people are clearly telling the movie industry that we expect not to wait a year for a movie to release on DVD.
The fact that you feel entitled to enjoy artists' work in the manner that you wish does not negate those artists' legal rights (or their agents to whom they have delegated those rights).
I'm sorry, I don't know where you're from. These concepts might be unique to anglo law. Property rights might work differently elsewhere.