As for the analogy with the F1, to my way of thinking, the thumbboard is more like the F1 with automatic gear and pillows(you do not need to know your scale and cannot play a wrong note by design!), but can be limiting in the more serious application. Just as a pro driver would need the manual shift(full chromatic piano keyboard) to do the trickier maneuvers like controlled skidding/turning(jazz and other styles requiring odd notes and multiple transposing mid-song). There is something to be said about being able to start jamming mid-song during a group session without having to find out what key/scale the group is using too. There is a reason why almost all hardware synths come with the standard piano keyboard after all.
I agree that a lot of the more innovative music app do not have the traditional keyboard anymore. It's just that TJ already has the best features and MIDI implementation on any apps I have come across that I would just LOVE to be able to use it as THE controller of choice for all situations.
From Jesse's comments I believe that he already understands what I am trying to convey. For those of you who don't, obviously you do not need a Piano keyboard, as most of you would have been attracted to TJ in the first place by the Thumbboard and that is great.
However I am sure that having the Piano Keyboard as well would allow Thumbjam to have a much greater appeal to the more "traditional" players and attract more new clients who may eventually grow into the Thumbboard like I have too.