The customers have many pages which display the document content inline, e.g. through "View Excel", "View Word" or "View Powerpoint" macros.
In these cases, there is no way to get into the attachment previewer.
A workaround would be to add an "Edit" link to the page manually. Not user-friendly.
An additional request would be to add an "Edit" button to the View Files macros. Remember there are many users which have already expressed the request to not obsolete this macro!
Sites which have the lock-point plugin installed, to make sure that an attachment is not concurrently edited by several people (to address the "last upload wins" issue).
For such sites, this flow is being enforced at the moment:

• go to the attachment page
• lock the document
• go to view mode
• view the document in previewer -> Edit with ...
• upload the change
• exit previewer
• go back to the attachment page
• unlock the document.
  This requires to navigate between the attachment page and view page 2 times. Productivity loss. By adding the "Edit" link to the attachment page, this would not be necessary.