[steveman]

What’s going on? Why haven’t we got 2t FI bikes with the adjustability that Yamaha have been doing for ages on 4t bikes?

That's what you will get soon, where soon means approximately up to 5 or 6 years. TBI is easier to manage than TPI for sure. A big problem is that most people think that smokers are less complicated than 4 bangers. It's true if we talk about engine construction and number of parts. However, the gas pulsation, the gas changes and the high sensitivity to pressure and temperature changes show a completely different picture. Two-strokes are far more complex than four-strokes.
A four stroke does not react if cold water splashes over the header, a two stroke does. And this is just a very simple example. Emission control is no problem in my opinion as -at least over here- 99,99% of two stroke enduro bikes have been uncorked and hence are illegal if driven on public roads.