I disagree. Both the assault rifle and combat shotgun are very handy for the aggressive player, especially with the alternative ammunition. By the end of Hong Kong I normally have a load-out of weapons something like this:
Prod. Baton. Dart Crossbow (Scope). Assault Rifle (Silenced). Sniper Rifle (Silenced). Dragons Tooth. Stealth Pistol.
Also a rotating back-up arsenal of ps20's, LAMs, gas and EMP grenades, and pepper spray. I really find the pepper spray useful earlier in the game. You'd think sometimes, with the scarcity of prod and crossbow ammo, that the game almost wants you to kill...but when going for a pacifist run (probably the 'purest' way of playing Deus Ex) pepper spray and the baton work wonders. One thing I only discovered after a few plays is that if you have the strength augs activated the baton can take down even quite significant foes with only one hit. That said, what I normally do is show mercy to NSF and Unatco personnel, and blast the everliving shit out of anything with an MJ12 logo or sunglasses. This is mainly because I have never managed to get past the prison level without killing anyone on any difficulty except easy, and even on easy I have only ever made it to the second Versalife level (though I did of course kill Anna Nevarre. There is actually a way of cheating your way round killing her by LAM climbing over the balcony in the Unatco HQ, thus avoiding trigger areas, and making her panic and run away through the door by throwing a LAM at her. The door is then open without killing her. Seriously though, way too much effort.) I wouldn't put this down to a lack of skill on my part so much as the fact that I find sneak-em-up play immensely tedious. Plus, of course, if you take the pacifist route, you don't get to use the dragons tooth, which is nigh unthinkable.