[Marc Sabatella]

Let's compare Nikon's lenses, since they offer both a lens that I like (the 18-105) and a superzoom, an 18-200.

The 18-105 weighs 14.8oz (420g) per Ken Rockwell. Price per Adorama: $360.
The 18-200 weighs 19.8oz (562.3g), again per Mr. Rockwell. Price per Adorama: $760.

Do the same comparison with Sigma and you get a different story, though. So I wouldn't assume an 18-105 will *necessarily* be a lot lighter or cheaper than an 18-200. For better or for worse, it appear much of the world's expertise in lens design has gone into putting more range into a zoom, and people are getting pretty good at it. The market demands this. So there just doesn't strike me as that much reason to expect a medium-ish range like 18-105 to have enough demand to get enough attention to actually produce better results.