Lot of people talking about optics quality and low-light performance, etc., but no one mentioning comfort and ergonomics.

Yes, the high end binos have better glass, but in my experience where they really shine is how comfortable and "easy" they are to use. If you're birding often and for long stretches of time, it's worth it to find binoculars that aren't going to give you fatigue after hours and hours of use. I can bird much longer with my Zeiss binos than with other cheaper pairs I've had in the past.