Blame it on the bean counters- - - - -the geometry of a properly-designed spring balanced hinge requires a lot of sophisticated engineering, and manufacturing the assembly costs a lot more than making a simple pivot and a prop rod or using a straight-push strut to keep the hood open, sort of!

As a quick aside- - - -in the event of an under-hood fire, that center pin of a support strut can become a deadly projectile. My nephew who is an EMT training instructor has some pretty grisly photos of wounds suffered by first responders when a hood or rear hatch strut gets hot and explodes, shooting the center pin out like a crossbow bolt!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!