Like with anything else you get what you pay for, don't buy a Yugo and expect the performance of a Ferrari, CRKT knives are probably a lot better than most production knives from the 50's thru the early 80's.
As far as the steel goes, 55 to 57 RC was perfectly acceptable, it wasn't until the Super Steels the Custom makers were using,(D2, ATS34, Stellite, ect) became cheap enough and readily available that we began to see blades with a RC of 58 and better, hell my buddies father still won't buy a knife with a stainless blade, because of the bad rap stainless got in the 50's.
Bottom line it's all relative, you get what you pay for.