It makes it very easy to edit migration files that have already been loaded into the development database. It wipes the slate and starts afresh. I’m never worried about the data in my development database as I usually use the test fixtures as development data, it’s standard practice for the projects I work on.
Without such a rake task, if I edit a migration that has already been loaded into the development database it can be a pain to rerun it with the changes. Often you can simply roll back to the previous migration then migrate up again, but that won’t work if you’ve also altered the downwards migration.
At least for me, it is much less work to just type rake db:reload
-Jonathan.