neutral neutral neutral flat flat flat flat, well many people don't like neutral or flat response signatures
A warm, wide, deep sound signature is preferred by many regular users that don't spend so much time analysing curves and frequencies
the 2.14b sound signature is dull and lacks impact and warmth
When we say we like more flatter and/or neutral sound doesn't mean we don't like bass or warm sound. We are actually comparing to a reference soure that we know is how something should sound like. And that neutrality means that the DAP, in our case the X3, doesn't add "colour" to the sound that is outside of what was mixed and mastered on the audio source.
I personally like some bass in my sound but not overly so. And when I listen to my test tracks, one of them is a baritone acapella solo that if it was too warm, it would be very easily become muddy and even unpleasant to listen to.
With that said, you can always adjust the tone with either the hardware treble or bass adjustment or the upcoming soft EQ setting in the 2.14 (or the 2.14b). Sound and music is always subjective and everyone in one way or another has an opinion on it. Please don't take this the wrong way and think I'm saying you are wrong. Far from it. I agree that the 2.14b does take away the warmer sound that was in 2.1. It's a good thing and a bad, like you said it does flatten out a bit more then what you're used to. But on the flip side, doing so, it does bring it closer to a "studio mix" feel to the sonic signature. It's a double edge sword here and no one way is correct. There will always be multiple camps of thought on this.