Businesses are required to have flexibility if they want to be able to service clients effectively. Users have little patience when looking for products/services online and can easily be turned away by the slightest mistake. This is why I fail to see the usefulness of Adobe Flash as a business application.
As a premier web designer/developer, I can easily say that there is nothing that I cannot whip up leveraging HTML, CSS, PHP, AJAX, etc... But I can say that the only difficulty I have is producing smooth graphical elements like sliding tickers, loading screens, or games. I see these things as having not being an integral piece of any business application.
Full size, Flash based websites lack one major design component: Accessibility. Users come from all places, using all hardware expecting to use your site.
Lets say you are a restaurant with a fancy Flash online menu. A potential customer who is wandering your neighbourhood is looking for a bite to eat and is checking out restaurants on his iPhone. They find your site and are immediately turned away by a blue brick of inaccessibility. Boom! You just lost a customer.
There are obviously ways to get around Flash while still using it of course. A simple HTML page to fall back on is one typical solution. But then I ask why not just make the website out of HTML to begin with? Avoid all of these '2 different websites' shenanigans.
In addition, you will undoubtedly pay more in the long run for site maintenance as well in this scenario. Site updates will have to be made to the Flash and HTML pages, essentially doubling your costs.
So if you are a business that is trying to drive business through the web in an accessible, cost effective manner. Build it with HTML.