Because it's easy? I have 100 static websites on S3. After initial setup of buckets, it's trivial to update/sync all of these sites using command line tool (I u

Because it's easy? I have 100 static websites on S3. After initial setup of buckets, it's trivial to update/sync all of these sites using command line tool (I use S3 Sync) with one click on a batch file. And hosting on S3 is cheap.