Using the View properties Read-Only works great, but not for file Attachments, as you have noticed. One of the oddities of IP I suppose.
The only thing I can think of would be to manually change each property to read-only. It can be cumbersome.
To get the attachments working on the read-only view where each individual field has been changed to read-only (since it won't work when the view is read-only):
The end users can then open the attachment, but cannot save any new attachments.