Yea it really is total preference. This is not meant to offend, but I think it depends primarily on how willing people are to spend a small amount of time to manage their stuff(And how much know-how they have).
For instance, I have my gmail public email, and a google-apps for my domain for my professional and personal. I haven't used an ISP email in some time, for similar reasons to what you mentioned.
I pay less than .mac for a web hosting service that provides much more storage, and has minimal requirements in as far as making things public or not. If I want them public I just post them to a subdomain. If I want it private I have a few options, one I can just SFTP it to a folder outside of the web area, or I can create a private svn, depending on the content. My photo galleries, I wouldn't use the default ones on .Mac for anyways, my website is my portfolio so it has to visually represent me even though it is an audio portfolio. The same applies to photo galleries as those show off the shows I have done.
But none of what I do is to tightly integrated(Some can be easily, MacFuse and SVN FS is your friend, and I have WedDAV available just the same
. For many people, theyeither don't have the knowledge, or don't want tos pend the effort(Not necessarily a bad thing) to do this, and for them .mac is a better choice. It all comes down to personal preference.