I mean I get your point and I do agree to an extent, but I feel I should point out that user data on iPad is largely in the cloud. This year if a student didn't have an iCloud backup (most did since they're automatic) and I had to replace their device, they were delighted to find that all their iWork data was in iCloud. Ditto for PDFs in the Adobe app. And ditto for Google Drive/Docs/Slides/Sheets. The only thing they might've lost is photos / videos / settings / extra apps, but iWork + Adobe + Drive cover 90% of their classwork. Even bigger bonus? They could log in to the cloud services from a classroom MacBook in the meantime to get to all their stuff if they had to wait a few days for their replacement iPad.
Now that said, using the Google Apps Admin Console to manage Chromebooks is 100x easier than using any MDM solution. And yes, I get it, all Chromebook data goes into Google Drive and therefore could be grabbed from any device / platform too. Chromebook definitely wins in the "easy" category. But it definitely doesn't in the "included functionality" category. I think for a vast majority of K12 students, iPad offers more than Chromebook (anything Chromebook can do, iPad can do and then some*... for now... and even then I question the usability and quality of Play Store apps running on a laptop form factor).
*Except Flash, I know, shut up that's totally not important.