You've got your 'old school' chits-and-counters on one side of this theoretical spectrum, and plastic toy soldiers on the other. I'd place your common Eurogame wooden pieces somewhere between those extremes.
Bits. They can make your game look a lot better than it is, or make a good game look like crap. They can work well, or be tremendously annoying during play. They can also be completely useless.
There's been a trend lately, led by Eagle Games (okay, they've been doing this for a while), Fantasy Flight Games, and good ol' Hasborg (fine, they've been doing it for a while too) to stuff as many plastic figures into a game box as possible. The function of this practice is pretty clear - appeal to the Army Men toy gene inside male gamers to entice them to buy a game. For the longest time Eagle did this a lot, with mediocre games like War! Age of Imperialism, Attack! (before the expansion) and Age of Mythology sporting lots of cool plastic figs adorning games that leave much to be desired. Hasborg never really stopped, most recently releasing THE game for young boys to have these days, Heroscape. Finally, FFG has Chinese factories churning our prodigious amounts of plastic figures to stuff into their "epic box" games - Twilight Imperium 3E, World of Warcraft and Descent: Journeys in the Dark, and the less-than-epic-yet-still-plastic-choked Doom. FFG also did the stateside release for Nexus Editrice's War of the Ring, no pushover in the plastic wars itself.
So, what do all of those games have in common?
The plastic pieces have little to do with the game itself. They're purely eye candy and have no impact on the mechanisms. They don't even carry any game information outside of whatever unit they represent. In some cases, the units are even functionally identical despite looking different.
I think that's just silly from a gameplay standpoint. Of course, to some marketing to the eyes is more important than actual gameplay, so you have the games presented as above.
Forget for a moment that I hate War of the Ring's mechanisms. Even if the mechanisms were good (say, Hannibal good) I still would have been unable to get past the tremendously annoying figures that not only choked up all of the board real estate, but were functionally identical. The physical attributes, the decision to use plastic over more sensible counters, would make me give War of the Ring a rating of no more than a generous 6/10.
Days of Wonder has so far shown restraint. The worst offender in their portfolio is Memoir '44, but that's a game that's targeted towards young boys who appreciate the plastic Army Men so we can forgive them. Its older sibling Battle Cry was a Hasborg publication after all. Ancients gave up on the plastic and uses far more sensible blocks. Sadly, BOTH sides of the blocks show the unit. I don't get it. Why not stick with the usual fog of war granted by block wargames?
The bottom line is that the drive of some companies towards using plastic figurines (a) prevents more meaningful use of the game component, (b) is often detrimental to gameplay, and (c) drives up the price point of the games.
Down with plastic. Go back to sensible cardboard counters.