From a Web Design perspective the narrative often has to come from the client and often many of the photos too. In an office environment the text may be dictated to a secretary. Photos may be in different formats some of which do not support Exif. Support for RAW format is developing slowly. I think the solution needs to be robust.
Agreed, but a partial solution for JPG-only would be a good start.
Right now, as you note, there are multiple ad-hoc (Excel, Neo-Office, cut/paste, etc.) work-arounds, but there is nothing reliable, and certainly no solution in sight.
In my view, AS is way ahead of the game by making text an integral part of photo/albums. PTW in this sense is a misnomer -- it does not create Photo-to-web sites, rather it creates photo-journalism sites.
EXIF had traditionally warehoused technical information about photos, but the photo and text world (files/formats) live apart until the are brought back together in (on-line) newspapers.
If we considered text as an integral part of a photo, then, yes, we need robust tools to make photo-text a day-to-day reality.