Gordon Lightfoot is full of major sevenths.

Beautiful

J.S. Bach uses them as passing tones. Most famous example, First Prelude from the WTC, the one used as the accompaniment to Gounod's Ave Maria.

Without this beautiful interval we would chuck all the works of Debussey, Brahms.

Simon and Garfunkel use it a lot.

Old Friends America Bridge over Troubled Water.

There is quite a lot of left handed literature for the piano and it is quite beautiful. I like it. But I would never say it shouldn't be played because it is different or difficult. Neither would I say it should be played to the exclusion of other literature.

The same is true with chords and intervals. Include them, don't exclude them. But don't include them to the exclusion of others. Don't limit your musical horizons.

Boromir