I am not a big fan of stickers either, but everything has it's market.
I'm an engineer,so this is gospel. The decal on the rear quarterpanel has a lower coefficient of friction and reduces the overall drag coefficent of the brick wall we call an Xterra in comparison to the regular paint job. It's a fuel saving mod that is totally acceptable. Also, in some parts of the country, "nismo offroad" means "don't run into the side of my truck you unintelligent deer", so it keeps deer away as well.
And it really does add 5 hp.
It also makes a 2000-2004 X look slightly unique.
I have to stop studying for my Corporate Valuation Exam, I think I'm starting to lose it.
John