If there were only two evils, I might agree with you. But there are better options than either of the two you mention, for example Preview on a Mac or Sumatra PDF in Windows. Converting to Flash makes it harder to use a decent program to view PDFs, picking evil for everyone, not just those who use Adobe Reader.
They should, but that isn't a solution to the problem in hand, as getting to the file I'd have to load the URL, click to load Flash, wait for Scribd to load, hope Flash on Linux doesn't crash, then click on the save button, then download it again.
It's worth noting that due to the separation of pro- options it appears like the board is divided down the center when, in reality, more than 2 out of 3 voters (about 68%) are in favor of Scribd support!