Even if we take your first question as true (and that is highly doubtful) it is far from clear that users prefer sites which "look more professional", cf: plent

Even if we take your first question as true (and that is highly doubtful) it is far from clear that users prefer sites which "look more professional", cf: plentyoffish.com It's also far from obvious that an all-flash site looks more professional than a flash-free one: if you want to make a site look tacky, just throw in some gratuitous flash or animated gifs and you're away.