By Winer's logic, shouldn't the iPad also support Java, Silverlight, Realplayer, Shockwave, Windows Media Player and Quicktime? There's definitely useful information locked into each of those formats as well.

Arguing that browsers should support plugins because they might be necessary to display useful information is a really slippery slope, and would be a wonderful way for Apple to get stuck in business relationships with notoriously incompetent companies like Adobe for little to no actual benefit. I'm not convinced that there are a significant number of people who would let the lack of Flash influence their decision to buy an iPad--certainly not a significant enough number of people for Apple to cede a portion of control over their platform to a company that has repeatedly demonstrated a complete inability to make Flash work on mobile (or really, any) platforms.