The TDP limitations is not only due to heat issues, but also to maintain the battery levels.
Sure you can ran the hardware at a higher speed with more TDP / wats, but you will also drain the batteries way faster.
That is why you will never see one of the "gamer" laptops with better battery then 2 hours (which is nothing as those numbers are of average use).
Not defending the "technical" solutions of Apple, because i think they missed the mark with MBP this time.
The touch bar is a gymnick, and the hardware a bit sub-scale.
I will wait for better CPUs and faster memory / SSD combos... maybe next year?