Just some thoughts on sheaths.
No matter how hard a manufacturer tries to offer the perfect sheath, some people will dislike it. It could be a sheath that's worth way more than the price of the knife it holds, or a cheapo just meant to enclose the blade: doesn't matter.
Why is that? The manufacturer may think that they're offering the best sheath on the planet, yet some people complain. It's because the manufacturer is offering what they think is the best sheath possible: not everyone agrees though, because everyone has a different idea of what a good sheath should be.
Sheaths are, in many ways, pretty personal things, and people's requirements vary, too. What's a good sheath to one person may be junk to another, and vice versa: it's a pretty subjective thing, actually.
Some people love leather sheaths, and don't want anything else. I like leather myself: I like the look of it, and the smell when it's new. If my knives stayed home as objects de art, they'd have leather sheaths. My knives go to the field, though, and get the holy living stuff beat out of them (that's why I use Beckers, boys and girls), and the sheaths take the same abuse: I am not gentle.
Cordura sheaths? Great. They're fine, as long as they have a kydex insert — and they're configured just the way you want them. The problem is that there are almost infinite ways to make a Cordura sheath; the pouch configurations alone can vary enough to insure that not everyone will love any particular design.
Kydex? Actually, kydex is my favorite. It's impervious to almost everything, holds and protects the knife well, and can be setup just the way you like it. Take a look at the sheath on the BK-2, for instance. That thing has enough holes along the edges for a creative person to strap on more stuff than they want to carry, and still have holes left over. Get the pouches of your dreams, and strap them on: instant modification.
I think a manufacturer designs the best sheath they can for a given knife, and hopes for the best, knowing that it won't be perfect for everyone: I think they do the best they can, especially at the price point of Becker knives. Some of us will like them, some of us won't. If we like the provided sheath, then that's cool, and we don't give it much thought after that. If we don't like the sheath that comes with the knife, we're free to modify it or get another one that we do like.
As far as the Becker kydex sheaths dulling blades, I've never had that problem, and yes, I keep my knives shaving sharp (a man has to have a hobby, right?). I'm careful to draw my knife straight out, with the pressure on the spine, though. Maybe I just got good sheaths; maybe I'm just lucky; maybe the stars smile upon me: I don't know. There have been enough complaints about this though, that it must be a real problem for some, and I'd be interested in finding out why it happens, and how to fix it.
If I wanted a kydex sheath for a BK-7 or BK-9, I'd probably just contact Marion David Poff — one of the board members here who does Becker kydex — or one of the other makers, and git 'er done. Same with Cordura or leather.
Me? I like Becker sheaths. Maybe I spent too long in the Corps where we took what was issued, modified that to our liking, and used it. I'm kinda the same way about Becker sheaths: they work, and they work very well, which is all I ask of them.