People often use frames to provide an easy to maintain site.
The same is true for a header or a footer that stays static while the content is scrollable. Some companies like this so that the corporate logo and contact information are always visible and easy to find. Using frames on a flash-enabled site is one way to get content indexed by search engines , as at present search engines can't spider the content in flash. As an argument against frames , the easy to update debate can be quashed by the use of server side includes which are probably easier to maintain than frames. And while having the company logo and contact information visible is important, this can be achieved by having pages which don't scroll too far down.