Rock Knocker,
Most of the other answers on this thread so far have touched on several of the issues you're asking about, and most have been to some degree, correct. The real reason for the hollow point design, is as has been alluded to, the manufacturing process. Prior to the intoduction of the hollow point match bullet designs, most match bullets were of FMJ configuration. Problem here is that it's considerably harder to make an accurate FMJ than it is a hollow point. To begin with, FMJs require massively thicker jackets, due to the extensive forming that takes place in order to create the ogive. Thicker jackets are harder to draw concentrically, providing one source for accuracy loss before the bullet is even formed. If you look at how the jacket is formed, you'll see the problem; essentailly, you're putting a point (the meplat) and ogive on the flat base of a drawn jacket. Remanants of this radius can often be seen as a "frosted" section on the ogive of formed FMJs. With a hollow point design, you can begin with a thinner jacket, which is in turn easier to draw concentrically, making for a more inherently accurate finished bullet. The forming involved here simply entails putting the ogive on the jacket once the core is in place, creating much less stress on the jacket itself. The meplat size is, as mentioned, limited by the size of the knock out rod that punches the formed bullet back out of the die. Most of todays modern hollow point designs run somewhere around a .045"-.060" meplat, because that's about the limit that currrent metallurgy allows for a knock out rod that is both tough enough and hard enough (not the same thing) to consistentily push the formed bullet back up into the fingers so it can be moved to the next station. A larger knock out rod makes for a stronger punch, but a larger meplat on the finished product. A smaller rod makes for a smaller meplat, but too many wrecks where the rod fails to punch the bullet out, and the press tries to seat another bullet on top of the first. Expensive and time consuming mess to straighten out, so it's a balance between the two extremes. right now, that's just where the technology stands.
The idea of a tipped bullet, be it polymer or some other material introduces yet another component into the mix, and this degrades accuracy. basic rule here; the more complex the manufacture of a bullet, or the more component parts a bullet has, the more you're going to reduce accuracy in most cases. Essentially, you're giving Murphy another opportunity to interject himself, which I assure you, he will. Simple is good where bullet design is concerned, and the simpler, the better. Tipped bullet do have some undeniable applications, primarily (IMO) in varminting applications. The addition of a polymer or resin tip is basically nothing more than a windshield. It gives a much more aerodynamic profile to a bullet that uses a massive hollow point. That same exact bullet, without that tip, would have the BC of a Pringle's potato chip, and fly about as well. With the tip in place, it's now much more streamlined, delivers much higher BC and is still about as explosive as C4 on impact. Whatever slight degradation in accuracy may exist, is more than offset by these advantages. In short, they have their place, but they do have some drawbacks that keep them from being ideal competitive bullets in most venues. I shoot Service Rifle. The notion of finding little green polymer tips floating around in my trigger mechanism after a string is the sort of stuff nightmares are made of, and yes, I've heard of it happening to others. In a bolt gun, chasing game, no problem at all. As I said, everything has its place, and it that place, it's the ideal solution.
