DMOZ is not a listing service, never has been and never will be.
Yes it is. When you have a site that has tons of links in tons of categories, and a page specifically to let people suggest adding their site ... that's a listing service.
If you don't want to be a listing service, then remove the submission functionality and replace it with a simple Contact Us form. Then, you can go about reviewing and adding sites as you wish. You can even surf for sites yourself if you want to. And when you say "you can't submit, you suggest to the editors to look at a site", it'll be completely true.
Or, if you do want to be a listing service, which everyone expects you to be, then I think it's obvious that it won't work without many many more editors.
charging for listings It would be against DMOZ social contract
Does that mean you can't charge, or you don't want to? If you want to but feel that you can't, that's easy. Shut down DMOZ, start a new directory with a new name, and give away DMOZ's data to the new directory. New directory, new social contract.