Mendelssohn

It was the 200 th. anniversary of Mendelssohn's birth on Feb 3rd this year. According to Alex Ross, writing in The New Yorker, and quoting Goethe, he was far greater a young composer than Mozart; Goethe knew them both and he avered that Mozart developed in his late teens into a great composer whereas Mendelssohn was great from aged ten or eleven onwards.
But Mendelssohn's talent waned after his early twenties whereas Mozart's matured.
I always think of Mendelssohn in the same category as Saint-Saens: some of their music is too light to be taken seriously. And, in Mendelssohn's case in particular, some of his music is too deadly serious to be taken ... well, seriously. His oratorios are deadly dull at times. Maybe he was trying to shake off his Jewish nature by forcing a Christian message across which, though he became a Christian, he didn't really believe. Maybe he became a Christian for the sake of being able to carry on working - as did Mahler too (possibly).
I am going soon to a concert where a performance of Saint-Saen's Piano Concerto Number 2 will be given. It's a wonderful virtuoso piece for the piano, lively lovely melodies, a thoroughly enjoyable work, exciting to witness..... And yet? Is it a piece one can take seriously as art or is it a piece that is a sort of show-off party piece?
Saint-Saens wanted desperately to be accepted as a great composer but, in spite of his brilliance, never was. I doubt if Mendelssohn was as ambitious: he produced works that pleased but he didn't strive to please; and he produced works that were magnificent but he didn't strive to make them so. He didn't have to, they seemed to have come as naturally from him as breathing.