Everything in life is a trade-off, rockgeek, and weather stations are no exception. Davis makes just about the best consumer or "pro-sumer" grade weather stations around, and they have 4 ways of buying their flagship station: wired or wireless, with solar and UV sensors or without.
I would bet that they sell less than 25% as many WeatherLinks as they do weather stations. If they sell the hardware device, they pretty much have to include a program to access it right out of the box. And it's obvious that they don't put a lot of effort into making the software state-of-the-art. WeatherLink s/w hasn't changed much in years. As kray1000 said, you get it for free with the logger. Based on the forums to which I belong and the sites I've visited, I'd also bet that less than 10% of the WeatherLink purchasers use the software on-line. Most people that buy the logger want more than it has to offer.
I'll be one of the first to admit that Davis equipment is priced higher than their competition. However, that increase seems to supply a superior product, and supports a superior tech support program. Do a search, or hang around this and other forums and you will see what I mean. When I call Davis tech, I always get a US-based tech live on the phone right away. In the rare event that I need a part, it's in stock, and I have it in a few days. And those techs have been able to answer some really obscure questions on my part, like, "What algorithm does the VP2 use to calculate evapotranspiration?"
You are correct, though. The wired unit is limited compared to the wireless one, and most places that sell Davis don't clearly make that clear. But making a longer internal bus for a couple of inside temp sensors is not cost effective for Davis for the fraction of a percent of the people that would use it. One-wire or another bus might have been a better solution for you. Or, a wireless VP2 and additional sensors. Or, the best of both worlds, get Weather Display, and run your VP2 AND one-wire and have lots of sensors.
My Davis VP2 mantra:
Wired: cheaper to buy, harder to install, easier to maintain, more interference proof, more limited in sensors
Wireless: more expensive to buy, easier to install, harder to maintain, more interference prone, more sensors
Based on the above, I have a wired VP2 Plus.