- open the hood wider
- open the hood more easily
- avoid using the obstructive prop rod (though I would leave it installed as a backup).
I was considering the purchase of a Chevrolet TrailBlazer and a lot of those folks had installed a set. Thankfully I've come to my senses and we're now awaiting delivery of a 2001 4x4 Limited. 3rd Gen, if I understand correctly.
I'm going to guess by your question that 4th Gens come stock with self-supporting hoods.
Check out the 2005+ Tacoma forum on ToyotaNation.com. There's quite a few members who added them to their Tacos. The Taco doesn't have hood struts and uses a prop rod.