If you're wondering why some mods don't approve explicit images, then I should explain why I in particular don't, since I've got no explicit images under my belt as an approver. Doesn't mean I've not uploaded it, but my interest in this site changed a little, and I wanted to standout, so I stopped uploading pornography.
It also has to do with the images themselves. A lot of pornographic images are well drawn, but a lot more of them aren't, and many times people skip physical accuracy to make really strange pictures that just don't look right. As a newer janitor I can't say I trust my judgement just yet with them, but I know there's janitors who don't mind, and have pickier standards, and they know how to differentiate those physical standards better than I naturally do.
That the moderation staff and approvers are light on consideration for them is probably because we've all seen waves of these images, and it doesn't make them special or have artistic merit. Yes, there's good ones, and even great explicit, and those do get approval, pretty fast in my opinion.
A lot of those images are "faceless male? Check. Random cumshot? Check. Ahegao? Check. The problem with that is that unless the art is stand out, by nature most of those images just aren't special in any way, and even if they're closer to well drawn, their artistic merit is so dependent on a great understanding of or respect for good anatomy, which wasn't their intention.
But that's my reasoning, I can't speak for the others, but I'm sure they'd give you similar responses. We don't force each other to approve things we don't like, cause that's not how danbooru approval works. Honestly, I always thought it was the non-explicit images getting the shaft before, but now there might be more to it than that.