The remote merely releases the latch. It's not meant to open the trunk lid. Cadillac did away with the motor driven trunk lid I think in '02. My '01 Eldorado had it. Owners were breaking them right and left by slamming the trunk lid closed and breaking the mechanism.
The trunk lid was designed to just unlock and not fly open when you hit the trunk release. Plus, it often takes a bit of effort to lift it open once unlocked. This has been a common complaint. I think in a past thread, someone said that the design of the trunk lid mechanism (on the sides, and out of the cargo area) wouldn't support an auto-open feature.