I use bar ends simply because I got a very good deal on them and upgraded from the low-end brifters that came on my road/tourer. For a racer, the biggest advantage may be the ability to shift easily from a majority of hand positions, especially while in a tight pack of bikes. I don't race, and don't generally enjoy riding too close to other people, so this is not a concern for me. Ease of maintenance may be inherent in the fact that it's a slightly older technology. That's not to say brifters are unreliable--I haven't heard anyone say that they are.

I too ride on the drops more than many people, especially on shorter rides around town. Bar ends are conveniently located from that position. I do also like the "clean lines" formed by using bar ends, as opposed to dangling cables, but I'm wary of that logic, as it inevitably leads to fixed gears, complete with sawed-off rack eyelets and messenger bags