From the original design of the TPI (Tuned port injection) motors built in 1985, GM did a fine job running the coolant through the throttle body (all aluminum) and the EGR was built into the aluminum intake. Therefore, we never had a problem until the invention of plastic intakes. I assume that a co-op Engineering student in training, designed a plastic intake and convinced his boss and Sr. staff that they could increase their bonus potential with a new cost savings idea, and they all jumped on the gravy train. I spent 40 years inside "Corporate America" and know how the system works. Penny pinching is the only way to increase the "bottom line" and get those big bonuses.
Plastic is cheap, and the throttle body still needs heat to keep the throttle plate from freezing in extreme temperatures, therefore the design was implemented without long term testing.
Ford also jumped on the gravy train and used a similar design, however at least they had enough balls to do a recall their cars with leaking intakes!
GM will never have a set like Ford!
