In 2016 having a fuel mixture in a plane makes me wonder why is that needed; not only that some popular engines (like Rotax 912 family) do not need it, but proc

In 2016 having a fuel mixture in a plane makes me wonder why is that needed; not only that some popular engines (like Rotax 912 family) do not need it, but processor controlled injection engines definitely do not need it. Fuel mixture is so 1960 and carb heat so 1990... (I'm a pilot in my free time flying propeller driven 2 seaters).