My profession is electronic engineering and also being a mechanical engineer I was originally horrified at the lack of innovation when I started flying.
Now, 11 years later, I can see good reasons for a lot of it.
A lot could be improved but the thing which is holding back those bits is not "certification costs" as we are all repeatedly told. In fact any big player is perfectly capable of getting some new widget certified. It doesn't even have to be reliable to get certified - Thielert showed that one pretty well... The reason things are held back is partly a widespread ineptitude in the industry, where the big players are packed with old fogies counting the days to their pension, and partly the fact that "the market" is the USA where you cannot afford to screw up. If you "did a Thielert" out there you would be dead and buried for a hundred years. That's why Diamond sold the
avgas DA40 out there (with a SE you don't want a dodgy motor) while "market testing"
the DA40TDi over here.