Dear @sebastian
Thanks for your post and initiative. We are using Imagor in Neos Zebra projects, so not directly from Neos - we just pass a reasonably big image to the Content API and then use this image to apply additional processing in imagor (mostly smaller versions for a srcset).
I also think that processing images in PHP is somewhat outdated, especially performance-wise. And especially in Neos, having all the variants as assets in the database sometimes feels strange, especially if they are just the (otherwise unprocessed) smaller versions of an existing image. However, since Imagor itself is an external dependency and currently it’s still possible to flawlessly use Neos on a simple shared hosting, I would not make this a hard dependency.
Reagarding Imagor Studio:
I would be very much in favor of integrating Imagor Studio. Cropping images in the backend is of course nice, but even CMSes as a service (such as Wix) offer much more:
This would be a good selling point, because it means convenience for end-users.
Regarding the implementation, I think you could consider the current crop editor and Imagor Studio as an abstract concept like an “Image Processor”, so maybe the crop editor could stay, but it can be replaced with the more elaborate studio.
As a side note, there’s a concept for another extension of the image cropping functionality: Focal points. It would be nice if the two goals wouldn’t clash.