[I said I'd go hibernate, but what the heck, I might hang around for a bit on this thread]
Unless you take on board Mozart was as much a violinist you'll not understand his music. Also his touch - on his piano the keys hardly moved (5mm at most). It's a weird kind of static, extremely precise experience.
He was at least as much a violinist as a keyboardist, and I think more as a keyboardist. And I know Mozart's keyboards well enough to know what can and cannot be done with them. Your point?
An odd term to use. Scales and arpeggios (being broken chords) are the building blocks of classical music;
Indeed. And chucking a million of them without very good musical purposes does not constitute the making of a masterwork.
you need to appreciate what's behind the decoration in order to fully understand and enjoy what Mozart is doing here.
I understand them perfectly well, and appreciate them for what they are - garbage.
Perhaps at this stage I should clarify once more...I say all this with his later, mature works in mind. These earlier works are pretty good stuff, but if they are all that Mozart could come up with, there is absolutely no reason why the likes of Clementi, Hummel, and whoever else has been mentioned here should not feature SO MUCH more prominently in the concert stage today. The point is, these earlier works by Mozart really pales in comparison with his mature works, which are absolute masterpieces of the keyboard repertory of all time.
The reason these concertos are not as often played as some of the later ones is nothing to do with poor quality; they are scored for reduced orchestral forces (they can be played with string accompaniment alone) so don't fit easily into the average concert programmes of a full symphony orchestra.
In that instance, there should be a million community orchestras (who obviously don't have a full orchestra) playing these concerti. But no, they pretty much always choose Mozart's later, more mature works. Besides, how hard can it be to shift a few chairs around and remove a few orchestra members in between pieces? Full professional orchestras do it all the time anyway.
So obviously the music is more important than mere stage practicality...and your point thus disproved.
As for the other A major concerto, K488, which you mention, it is indeed a marvellous work. Nevertheless, although it is one of the most popular there are many who know their Mozart very well indeed who rate it as one of the slightest of the later concertos and prefer such works as K453, K482 and K491.
Indeed, those concerti you mention do serve as excellent examples of how great Mozart's music can be - and similarly, pales the earlier concerti in terms of musicianship and craftsmanship. I personally prefer that A major simply for being the very first Mozart concerto I came to know.