Google killed this argument last week when it announced that this is a shortcoming of the past.
from Google Webmaster Central Blog:
“Google has been developing a new algorithm for indexing textual content in Flash files of all kinds, from Flash menus, buttons and banners, to self-contained Flash websites. Recently, we’ve improved the performance of this Flash indexing algorithm by integrating Adobe’s Flash Player technology.”
To me, Flash site development still tends toward tiny unreadable text and annoyingly long page transitions. I like Flash, in it’s place – there are things that html still cannot do that flash can ( even with the help of ajax)… But do we really need more All Flash sites?