Why would you do that to yourself? You're illegally downloading content. It's really cool and good and all that you're making up for your illegally downloaded content by actually purchasing the movie afterwards because that is what matters, but you could still have to pay huge fines for doing that if anyone wanted to make you.
The other thing is that I think good natured people like you who want to pay for movies after watching them are very rare. The majority of pirates don't follow by your way of thinking, I would guess.
You know why? Because there's so much shitty content out there. Bad TV shows that have one good episode. Bad albums with one good song. I'm sick of buying stuff and then later discovering I was simply a victim of a marketing campaign. That's not fair.
So I will see if it's any good, THEN I pay you. That's how it should work, just like it does in a restaurant: you consume their content, if you're unhappy with the product, it's acceptable behaviour to complain and not pay. Why should I pay them to waste my time?