Today most webmasters look at ALT tags as a way to stick few more keywords into that page. Some stopped using ALT tags altogether, being afraid that they might get banned for spamming the search engines. Few realize that image ALT tags are actually there for a purpose. Originally they were used to cater to those users with images disabled in their browsers. However, with the age of broadband, such users virtually disappeared. Another reason why using ALT tags might be beneficial is the fact that your website will be more accessible through handheld devices and cellphones. Yet another reason has to do with the lawsuit mentioned above. Screen readers, which are often used by visually impaired users, rely on actual text in order to extract information. That means that nothing about your images or Flash animation will be understood.
These things are something you should take into consideration. Designing your website with all kinds of people in mind might benefit you in many ways.