It is true, I develop a lot of stuff where the documentation lags by months, sometimes even years.
But documentation is tricky. A perfect example would be the versions of Arduino the Teensyduino installer supports. Often people have complained this wasn't documented, when they couldn't get the "Next" button to enable. Of course, it's pretty plainly documented on the download page and also on the installer's first screen. The trouble was people simply didn't see the info in those locations. This has been on my TO-DO list for a long time, and finally in 1.20-rc5, I added a help button beside the "Next" button. It's still too early to know how effective that little "?" button will be, but my hope is it will finally solve this long-standing "documentation" problem.
Likewise, with the specific question on this thread, design of the pinout card is tricky. On Teensy 3.1, that card has now on it's 7th revision. It's difficult process, to balance the need for detailed information without causing "information overload". Even from the OP, the card at least gave the general idea that A10-A14 don't have digitalRead() capability, so even if it wasn't perfectly clear, it seems to be on the right track.
For more than 10 years, even back in the height of the 8051 days, I've dreamed of someday doing actual usability testing, where we get people to come to a conference room and watch them (fail to) use the website and product, and hopefully gain some insights. I even bought a few books, and (a couple years ago) loaned the
best one to a friend who we were going to pay to help us do this. But that was shortly before Teensy 3.0, when there wasn't a mountain of awesome hardware features in need for software support.
Lately, website updates have slipped, mainly due to so much work on the Teensy Audio Library. I know Steve isn't terribly interested in audio, but many people are. I am. It's been a long-time dream of mine to write this library. In fact, one of the reasons I went with the Freescale chip (rather than the only other chips available 3-4 years ago, from NXP and Atmel and Luminary Micro) was because Freescale had DMA and I2S. Even the audio library, with probably more comprehensive documentation than most other things I've written, is _still_ in need of introductory a couple videos. Detailed documentation isn't enough.
So, the best I can tell you is I really do care about this stuff. I'm aware documentation is lacking, and I'm also very aware that some of the stuff that is well documented isn't found when or where people need it. I do intend to work on these issues. I also am working on two more Teensy 3.x models, which I really want to get released this year. Ultimately, there's only so many hours in every day and far more to do than will ever get completely finished... but I'm trying!