PornBox.com

I think the trailers for OTS and PornWorld releases seem very short and only showing the first 30 seconds of the shoot. Also the descriptions are very brief. I don't want to risk buying an OTS shoot.

I agree

Yes, it's a pity. I think that the most of the users skip these contents, potentially good, because of the poor trailers and the excessive prices.

I guess the content makers don't provide professional trailers, and Pornbox don't have the resources or inclination to do it for them.
Seems to me content makers limit the sales appeal of their own content by not making the effort to make promotional trailers. But that's their business.