I don't see where any of the above is a 'revelation' -- though of course it is good to know.
It is also no great secret that music scholars and some musicians, littered throughout Europe, were constantly aware of all the earlier modal contrapuntists as well as the later work of Bach.
Yes, he sighs, Mozart knowing of Bach after his introduction to it by Baron von Sweelinck in....
1782 - age 26; nine years of life left
'Great' Mass in C minor (incomplete)
1783 - age 27; eight years of life left
All his modal counterpoint, known since childhood, could readily be the main 'source' of his contrapuntal usage here. That older counterpoint is evident in almost all the work from his mid teens, always 'showing' in the horizontal treatment, the lyric quality, in so many of the instrumental ensemble works he produced throughout his life
Mozart meets Haydn, 1784 - age 28; seven years of life left
Adagio and Fugue (the most telling that he was clearly working within the 18th century style of Bach) &
Symphony 41
1788; age; 32 ... no time left.
Mozart lived without knowledge of Bach for twenty six of his short twenty-five years, over three-quarters of his life. He had studied the old modal -- Gasp, Non-Bach, Non 18th century species counterpoint -- got along just fine til then, thank you.
Mozart heard, just once, the extensive and elaborate Miserere of Allegri, a work of many voices in the modal contrapuntal style, and then wrote it down from memory, perfectly. He was 14 years old at the time (1770.)
http://www.youtube.com/watch?v=36Y_z...eature=related
For A composer who penned his fifth and sixth symphonies around the age of 10 or 11, who took down the Allegri from memory at 14 (he either 'got' the old counterpoint in a trice or had studied it Already) the influence of Bach may be noted, and of some influence int the instance of the Fugue. For the rest, the man was well versed and in practiced for three-fourths of his life, and already habitually thinking, in those terms. The finale of the 41st symphony is a triumph, it is as 'modal' in its M.O. at least, as it is 'Bach influenced,' motets and simultaneous multiple melodies and canon well in use before J.S.
Your point is well-valid, and it is not nearly as great an influence as you'd like to make of it. Bach is noted, too, for being of no tremendous influence on the shape of music history, not a point against, just a fact.