>..., then you'd be stealing content from other sites. That's not very nice. In certain cases, you'd have to copy an awful lot ...
Um, let's avoid accusations of criminal behavior here, shall we? And anyway, in THIS country (and I suspect even in most other civilized countries) a directory doesn't and can't very well own someone ELSE's URL, now, can it? Or ... you have a contract that says the webmasters can't permit anyone else to link to them, and you don't realize that such a contract can't be enforced against any other webmaster anywhere? I really don't know where you're coming up with this, but I think it's from an alternate reality I'd not want even to visit.
>...and even create categories which are not listed on the ODP...
OOH! tempting, very tempting! There isn't anything in the ODP that's much more fun than that, as any active editor will tell you.
For small directories, "sucking out the juice and spitting out the husk" is without a doubt the best thing to do for the surfer. And it is also obviously the best thing to do for the websites represented in the other directory.
So ... when someone sets up a directory, allegedly to promote OTHER websites, but gets their knickers in a knot because someone else wants to help them promote those same websites, it is hard (OK, it's flat impossible) not to assume malicious ulterior motives. If those websites aren't worth listing, then why were they listed? If they were worth listing, then why shouldn't someone else list them? And how could anyone not be happy that their service to their customers (whether surfers or webmasters) has resulted in additional benefit to those customers?
OK, maybe the ODP approach is so different from your attitude that there's no way to even talk. There are certainly folk who think the ODP is plotting to take over the world, because that's what they'd be doing. And there's no way to tell them any different.