Refresh my memory, what cars are you referring to?
Yes they have come along way, the 53 Chevy posted has dog leg door and hood hinges and sold for $20.00, BUT when that car was made all the other 1/18 cars being made also had dog leg hinges. Every 1/18 diecast company had some issue on some cars over the years.
If you are comparing 20 year old regular issue diecast cars to high detailed collectible cars of today then yes, some may not look too good. By the way, Sun Star still makes many of the old cars with dog leg hinges as does American Muscle and a few others.