Also, there’s definitely an active community of authors using TADS 3. Just reading through the comments on that series of blog posts, I recognize a lot of the names from their participation in the broader IF scene or from reports on the Gargoyle issue tracker.
Part of the reason TADS has a lower profile on the forums is because it isn’t as attractive to newcomers. There are some technical reasons for that. Lack of browser support is cited as the big drawback these days, but it’s only in the last couple years that Parchment has come along, and it’s been less than a year since Quixe’s release. Before that, it was the absence of a full-featured interpreter on Linux and OS X. The official IDE isn’t as nice, and is still Windows-only.
Even in a world where those technical differences did not exist, Inform 7 would still have more “curb appeal” than TADS 3. It’s designed to be more attractive to writers, and the evidence suggests that it is. However, that distinction blurs somewhat among the initiated; a number of established authors are proficient with both systems.
Much of the buzz here can be attributed to the shortcomings in Inform’s design and documentation. If you took away all the “How do I do this?” and “Why doesn’t this work?” questions, you’d be left with a similar volume of posts in the Inform and TADS areas. It’s not that TADS authors don’t have similar questions, but there you can answer just about anything using the Library Reference Manual, and presumably everyone figures that out eventually or gives up in frustration.
Furthermore, if you look at the ADRIFT forum, you will see just as many novice authors and arguably a richer discussion of game design in theory and practice. Their community is relatively insular and the average quality of their games is somewhat low, but they have a lot of repeat authors, a lot of competitions, and a lot of games published every year. By nearly every non-technical standard, ADRIFT has greater momentum. It only lacks the promotional efforts of community celebrities like Emily Short and Andrew Plotkin.
Hence I see the decision to use Inform or TADS as making a choice to privilege the technical aspects of craft over convenience. As a consequence, implementation quality and portability count for a lot among the authors here. No one wants to put more effort into the programming side, only to be faced with crippling platform-specific bugs on release.
TADS has historically had a very high quality but monolithic reference implementation, and fared rather poorly on the portability metric. Inform is doing better these days, but two or three years ago the picture was different:
Git, the preferred Glulx interpreter, languished for several years after Iain Merrick moved on to other things. (His departure also halted development of HyperTADS for OS X, which would have changed the landscape for multimedia TADS.) Missing features and various bugs plagued the interpreter until David Kinder took over maintenance in 2009.
Inform’s indexed text feature was implemented for Glulx in a way that depended on Unicode support in the Glk API; as a result, only a handful of the existing Glk implementations can properly run new Inform games. All of the libraries in that list that don’t mention support for the 0.7.0 API are effectively obsolete now. This had the unhappy result of breaking the Glulx games in IF Comp 2008 for many players.
The small number of developers working on infrastructure means there will always be a lag between the desired availability of features and the corresponding implementation. Inform has mostly caught up at the moment, but there’s at least one major shift planned - the promised CSS / HTML extensions to Glk - and essentially no guarantee that everything will come along for the ride.