Mace, didn't have anything to base an opinion on the older Ares, I just know that the current gen and the S&T are a load of crap. The externals on the KWA (at least the older model) feel just as plasticy as the S&T "Competition" line. I've been running a stock JG (except a clone of the ICS Turbo motor) for 6 months or so without issue. The externals are pretty nice. The plastic is decently thick and has a nice feeling to it (at least for me). Again, I don't have much to compare it to, so I would probably change my tune feeling a CA or older Ares.
As for Umarex, I keep forgetting that they handle everything for H&K. I should amend my original comment to say "Why does Umarex continue to use the shittiest manufacturer for their guns?" G&G a step up for their MP5s, but S&T for the G36s that most people will end up buying? Bad move. As far as the trades issues, WE is Taiwan I believe. They're pumping out guns that violate the trade dress (or come extremely close to it) as far as Glock's, Beretta's, XD's, S&W's, ect. ICS is still pumping out Galil's and MP5's, they're just hard to find now. Then there's Tokyo Mauri, making all sorts of guns violating not just trade dress, but using full trades without any fucks given.
I think Chinese companies may be doing a bit of business with Umarex, especially on the LPAEG front. Otherwise, I know that Cybergun and ASG both do a fair bit of business with both CYMA and JG for their products. CYMA made the licensed Galil and still makes a Colt licensed M4 and the Kalashnikov AKs. JG seems to be making the Steyr licensed AUGs. Going through the ASG page on Evike it could any of the big Chinese companies making the new Armalite or Arsenal licensed guns.