WHATWG was formed because a significant number of members (including key browser makers) felt that the W3C had lost the plot. The two groupls mended their differences, but only after TWO YEARS, and the overall direction is now one that browser makers feel will make sense.
Every web author can write mark-up in the style that they prefer. The overall experience has been that valid (X)HTML on the web is extremely rare in every flavor. So this direction is one that browser makers can and will move forward with and support, without placing intense barriers in the way of the average web author.
In addition, the recommendation is getting extremely large mostly because it is a lot more ambitious:
1. There will be uniform error recovery recommendations. No more cross-browser differences!
While many of us here may approach (X)HTML as a kind of code, this is far from the norm in the world. Incorrect code fails - whereas browsers have long tried to render invalid mark-up as best they can. Most web authors are very used to this situation and lazy about valid code. But if the browser makers had done it differently, the web would not have grown as fast as it did.
I see these new directions as being eminently practical rather than academically rigid - which is the direction the W3C was previously going. The real world issued a wake-up call.