But without the income from the paying users, the site could not be run in that professional way. From this follows that they should determine the jury or vote for the IOTD. I do not say that this democratic process is a must, but I feel that the acceptance would be much higher then
Democratic systems have been tried in the past. There was a time, when Astrobin was small, where these badges and IOTD would be awarded purely based on likes. I guess that's as democratic as it gets! The imperfection of that system is obvious, so it was changed to judges, submitters, and reviewers, which is what it is today. The number of submitters and reviewers was enlarged about three years ago. Some questionable images were promoted as a result, which is why the system morphed into current where multiple reviewers/submitters have to promote images to earn a badge. Around the same time, there was an election for judges. That is the only site wide election I am aware of. I don't know what the current process of selecting judges is or how practical it would be to have an election for judges, submitters, and reviewers.
In general, I would not be harsh on submitters and reviewers. It is a time consuming job to go through several images day after day and select the top five in your queue. Most are simply doing the best they can to fit this into their schedule. I think the bigger problem is with a system that judges images taken using vastly different equipment and conditions according to the same standard. Sure, Ayrton Senna can, on occasion, win a race with a Toyota Corolla, but I can tell you he won't be doing it often. I think change is possible and necessary, but I also think the current system works for people that have a lot invested in equipment and location, so there will be a natural resistance to doing things differently.