Blogging minister (or ministering blogger) and friend Victoria Weinstein -- PeaceBang -- noted that she posted only a few pictures from her sabbatical visit in Romania because of the cost of bandwidth.
This truth cuts both ways: heavyweight Web sites take a long time to download when the connection is slow. And if the connection is expensive, then you're costing your readers money. Or, more practically, writing off readers.
If you have a significant readership outside North America -- perhaps also Western Europe -- or want to, you need to have a site that makes the most of bandwidth, and not assume their service will catch up.
Such a site needn't be ugly. Indeed, the structure implied in a good low-bandwidth site is more likely to make the site more elegant.
For implementation ideas, I recommend Aptivate's Web Guidelines for Low Bandwidth.