The apps were not disabled. The export feature hasn't been working because of a bug on their end. It seams like the claim that Parse "firmly believes in data portability" is complete BS.
The data export feature was replaced by the database migration tool we launched on January 28 last year. We highly recommend using the database migration tool as this will ensure that all of your data is copied over and synced to your new database prior to switching traffic over. Tons of apps have migrated in the past year using the db migration tool.
It's terrible that you aren't allowing data to be exported anymore. You shouldn't need to setup a server and go through the migration process just to get your data out.
The prior export feature that allowed data to be exported in JSON format was great, but that was left broken without any explantation.