In this case, I liken the Internet to a parade. We're all marching along trying to stay in step with each other, yet stand out in our respective areas. Because of my catagory of web sites, I am near the the front of the parade and it is making a right turn. Your time will come when you march to the corner; what will you do? My bet is you too will follow the parade route.
The thing is, you are making a right turn while the rest of the parade is marking striate ahead.
At one time, 640x480 and dialup went hand in hand. But monitor real estate is increasing; broadband is overkill unless we write for it.
It was still recommended to design for 640x480 long after 800x600 became popular and 1024x768 after that. Now the idea is to have a fluid design that will stand up to any screen resolution, since screen resolutions is one of the last things we can control.
Now apply that to bandwidth. Like the screen resolution, you can't control the bandwidth of the end user. And in many cases, he or she can't control it either. The only thing you can control is the amount of data you try to shove down the pipeline, so it stands to reason that you should only shove in no more then what is needed.
Your turn is coming whether you like it or not. Innoviation, technology, increasing broadband user base ... all going against the dial-ups.
You know, the arrogance of broadband is one of my biggest internet pet peeves. Even if the most generous statistics are true, broadband is still on the margins. Yet, broadband users feel the internet must cater to their high-speed connections, dial-ups be damned.