Most of the complaints about inadequate security come from army reservists. Many of these folks don't really want to be there, and want to maximize their chances of getting back in one piece. The regulars, however, see it as, "the only war we've got" and a way to prove that they can do what they have chosen to do as a profession. For career troops, combat experience is a big plus careerwise. The regulars also have a more balanced view of the situation, and realize being alert has more to do with survival than some ceramic inserts or additional armor for your hummer. It's a culture clash in the military, and the media is making the most of it.
The standard vest will stop pistol bullets and shell fragments. Additional side and neck protection is available via add on items for the standard vests. Some troops may complain about not having these, but they are new items, only invented in the last year. The biggest problem with roadside bombs (IEDs) is flash (eye) and blast (full body shock) damage. If you wear your goggles, your eyes are pretty safe, but you are gonna get hurt from a shock wave, as there is no protection from that other than to see the bomb before you are on top of it and thus not be right next to the explosion. At a certain point it becomes like anti-missile missiles. How much protection can you afford, how often will you need it and how reliable will it be? It's a no-win situation for the army, because there are about a hundred casualties a month from IEDs. No one knows if ceramic plates and vest add ons for all would reduce that at all. But for a soldier out on the road, talking about protection is all about, too much aint enough.
Complaints of a shortage of protective vests in Iraq continue to appear. There's no shortage, and there is. There are actually more vests over there than people. But not everyone has the bullet-proof "Interceptor" vests. These require special ceramic inserts and priority is given to infantry and people like MPs who are escorting convoys. Of course, everyone outside a compound would like to have an Interceptor vest. Well, not everyone. Tank crews don't like them because they are too bulky.