^this is true and also you still have to reach down with barend shifters, that and they're more expensive.
No you don't, your position still stay the same, as the bar end shifter is a lots nearer to you than the downtube if not easier than stem shifter (which is not as easy as it sound), it's also accessible when you're in the drop, look how much higher it is compare to where the downtube shifter is in this picture;
Can you imaging descending and needing to change gear? not very pracitical on the stemshifter (unless you perfected the art of shifting with your chin).
No you don't, your position still stay the same, as the bar end shifter is a lots nearer to you than the downtube if not easier than stem shifter (which is not as easy as it sound), it's also accessible when you're in the drop, look how much higher it is compare to where the downtube shifter is in this picture;
Can you imaging descending and needing to change gear? not very pracitical on the stemshifter (unless you perfected the art of shifting with your chin).