maybe he means those phpNuke and postNuke sites. Almost all of them look the same except images and color. There are a few unique designs out there though.
When I think flash is appropriate, is intros (there are some very very cool ones out there, and intros are only to look cool usually) animations that as any other format would be ridiculous size-wise and slow, and maybe other stuff that can only be done in flash, or done well in it. Like mouse overs and stuff. that site xeofreestyle is very leet.
I think i would use flash for header images that just loop around and stuff. but I would never use it for whole site, or even near that. Like SR said, going back and things like that are features people like using, especially me. I wouldn't want to have a design I don't even like using.
recently I gave up asp and started learning php. i never thought about it, but asp is MS only, so nice and cheap (among other things) unix servers aren't gonna support it. php however, is all over the place. so almost any pay host is going to spport php. php has also proved to be really easy to learn, more so than asp. lol, but mySQL is something i haven't even touched yet...php without making use of a databases...so useful.