Because if you have apps that weren't written at a time that S3 pricing made any sense at all (it wasn't that long ago you could afford to buy a new file-server

Because if you have apps that weren't written at a time that S3 pricing made any sense at all (it wasn't that long ago you could afford to buy a new file-server and JBOD every month for what it would've cost to store a few dozen terabytes on S3) migration is a huge burden and expense. Really looking forward to EFS to take a big bite out of that commitment since it has reasonable pricing for projects with smaller storage requirements. Just switching a portion (photos) of the project with the most files to S3 took on the order of 800 (mostly developer) hours. At some point you have to decide what you can do with the hand you're dealt and wether you want to distribute those tens of thousands of dollars to your employees, pursuing new business or your own pocket; or reinvest it into an existing project despite having no mandate to do so. It's not an easy or cut and dry a decision to make (even today) for legacy projects IME. If you're starting a new project. Yes. S3 is the most reliable service in the AWS stack (AFAIK) by a big margin. The pricing is very reasonable today unless you're in the petabyte range maybe, and you have no operations overhead. Agreed it's a no-brainer.