Live music is a whole-body experience, not just a sense-of-hearing one. Headphone (or ear speaker, as Stax puts it), ignores the physical aspect of music. Our ears hear music, but our skin, organs, and even bones feel it. Headphone listening is a completely different experience than is loudspeaker listening, a more purely cerebral one.
The only genius I have personally known (that’s not my opinion; He was a computer programmer at HP, and they wanted to know just how smart he was, so had him tested. He also had perfect pitch, loved J.S. Bach, Brian Wilson, and Bob Dylan, and was an excellent songwriter. As proof of his intelligence, he elected to not pursue a career as a professional songwriter or musician ;-) preferred listening to music on headphones rather than loudspeakers. But then, he didn’t need to "hear" the music, he could just read the sheet music to achieve the same result.
When he returned from an assignment in Germany (HP sent him over to train some programmers), he had a new supervisor. He told HP he couldn’t work for such a stupid person (she was undoubtedly very smart, but he had a very low opinion of women, except mine ;-), and resigned. He took his 401K money, paid a year’s rent on a house, and spent that year playing computer chess and recording Bach music which he performed on the piano he had shipped back from Germany. What a nut! We were about to embark on a recording project when in 2008 he died of a massive heart attack at the age of 56. I feel extremely fortunate to have known and made music with him.