I'm not advocating a position for or against this proposal. If it's put into service, I will probably utilize it. I do, however, wish to point out the potential future conflicts with such a promotional tool.
What are you going to do when a certain book cover creates complaints from any of the members of this forum? Are you going to institute standards for content?
I certainly appreciate the opportunity to be able to turn off such a tool if it becomes obnoxious, but I don't think that's going to be enough when more and more authors discover it and begin to submit their covers to gain attention. Eventually, there's going to be one that creates debate. In case you're forgetting, removal of a cover from a post already caused a certain amount of controversy.
https://www.mobileread.com/forums/showthread.php?t=74302
If you're going to move forward with a project like this, you should be prepared to deal with these kind of issues.