SWG's dye system was based purely on the palette alotted to each item piece. Some had different or partial palettes (like some pieces of Mandalorian armor.) While it was acceptable, it didn't allow complete freedom and in some cases made it impossible to match some items.
EQ had a pretty cool system since you could pick any shade you wanted with an actual RGB scale. By far the best armor dye system I've seen. They were also craftable by players and to this day, still sell pretty well. Really nice part was, you could make your armor colors look like anything in the game. Wanted to make your armor look the same color as the old Velious faction armors? No problem. Just put in the correct RGB (which you could look up on the web) and voila. I had a fondness for Cobalt's deep gray blue shade and still use it on my warrior.
Every other armor/clothing dye system I've seen in MMOs has been a poor immitation. The one they just added into SWTOR is just a step above Lord of the Rings (which is the worst.) Light this, Medium that, Deep whatsit. I'm guessing we'll be lucky to see 3 hues of each color and many lack the metallic sheen some color effects have. I guess that means they'll add in matte, glossy, metallic and so on as well.
Don't even get me started on the "collections" system. CE items, crystals and other junk aren't even correctly added. And for some odd reason, I have a few war hero crystals which I never use. The only war hero crystals I've ever had in my inventory are cyan ones I've made to sell (which was over a year ago since I made one.)
I give BioWare a big golf clap. Sure glad Legacy of Romulus is out in a few days. At least I won't be able to finish that whole expansion in a day like Rise of the Hutt Cartel. It's entirely f2p with few limitations, if ya wanna check it out.