I've spoken to many who just don't like the sound of Electrostats. I'm just wondering why.
Your guesses are pretty good. Some of it is due to people being used to headphones that distort, so that's what they expect and [think they] want. Think about the studies that have found for most people, a lot of the pleasure of listening to music comes from predicting what's going to happen as you listen along, and so just by sounding different, in any way at all, they can easily be perceived as worse. The way around this is to take the time to get used to the sound. I believe that the majority of listeners will come to prefer a distortionless sound the majority of the time, but nothing will ever be absolute.
E-stats are very revealing, I don't often enjoy using my Stax for streaming music, or for most 128kbps mp3s. If you only stream music and aren't interested in changing, dynamic drivers are ideal for masking the flaws in a recording. And even on clean recordings, more detail isn't always preferable, but that's largely genre-dependant IME. Nobody needs to hear the bass player farting or whatever. But I listen to electronic music usually and for me, more detail is almost always better.
For me, electrostatic are inherently more fragile than dynamics. I've had two O2s that developed temporary channel imbalance due to the humidity (I believe). This is why I got rid of my stax rig.
Fragile is really not the correct idea here. They won't all last forever, but Stax specifically are renowned for lasting 40+ years without the slightest loss in sound quality. There's no tiny voice coil wire to break, the sole moving part is the diaphragm itself. Not what I'd call fragile
Channel imbalance is indeed a common issue for older e-stats, and unfortunately it sounds like you weren't educated about the idiosyncrasies of e-stats before getting yours. I know how easy it is for a problem like that to infect your mind and ruin your ability to enjoy something. It's like when I plug earbuds in after listening to headphones without turning the volume down first, and they play super loud for a second or two. I always think they're blown now and I will literally hear faults that aren't there for the rest of the day. That's what my brain expects to hear, so that's what it hears.
I think the occasional imbalance is just the price you pay for the performance. As well as the actual price of buying them
Humidity may well be one factor, but it's certainly not the only one, maybe not even a major one. I live in the desert (<10% humidity most days) and imbalance still happens. But it's a minor annoyance next to the unmatched sound quality