The Difference Between Composition and Improvisation

Gunther Schuller caused quite a stir when he published his analysis of Sonny Rollins solo on Blue Seven. His point (ostensibly, that a jazz performance can make use of motivic development both as extensively and effectively as a classical piece, and therefore deserves to be taken just as seriously) needed to be made, remains valid, and is well taken by this writer. I do, however, want to offer a slightly different perspective based on my intuitive reactions as both a listener and a player, which is that while motivic development is (usually) nice when it happens during a jazz solo, I believe that jazz (and all improvised music) stands on its own as serious music even in absence of this device. In fact, I actually think that it is important that it is not overused, and that it does not dominate one's approach to improvisation.
The reason I say this is that improvisation is, well, improvisation. You could call it "spontaneous composition;" indeed, there are many famous and infamous quotes from jazz legends about the extemporaneous nature of soloing. The most incisive, however (from Steve Lacy if I'm not mistaken), is the one that acknowledges the most important consequence of this distinction between composition and improvisation, namely that improvisation does not allow for revision after the fact: once the music happens, it is out there and then it is gone, whether the players realized their musical intent(s) accurately or not, and whether or not anyone listening is even aware of this. This is the challenge that those of us who improvise (in any genre) accept each time we step out, but it is not a challenge to create the same thing spontaneously that we would create through composition and revision. While we may work at perfecting our technique and approach, it would not be worth the trouble to attempt to truly become spontaneous composers. If we so valued the opportunity to revise and perfect smaller details of the performance, improvisation would probably be the wrong medium for us.
Of course, one must draw the line somewhere. By this logic, even technical proficiency could be labeled a mere "detail" and thrown out the window. Obviously, this is not quite the point I'm trying to make. Of all the various challenges faced by the improvisor, effective motivic development is probably the hardest for the musician to create spontaneously (and in some sense, also the hardest to create with much forethought and revision; just ask a composer). In a sense, in puts the player in the same position as the listener in that they must perceive and follow the progress of such development in music they are hearing for the first (and perhaps last) time. In this age of home recording and internet distribution, perhaps it is more valid than ever to value motivic development in improvised music; nonetheless, it simply cannot become the be all and end all of improvised music because that is not what improvised music is. It is a question of choosing the right tool for the job: one does not use a hacksaw to cut down a large tree because the hacksaw is needlessly cumbersome on account of being too small and not sharp enough; similarly, to choose improvisation as one's medium for creating profound motivic development akin to that traditionally valued most highly by European classical music is, while not fruitless in every case, certainly a more cumbersome way to go about it.
In this sense, motivic development taken to extremes in an improvised context is essentially another form of empty virtuosity, just like playing high or fast simply for the sake of playing high or fast. I have always felt (and this is, of course, an opinion and not a fact) that the traditional jazz approach of improvising on the harmonic structure of the tune lends every such performance a sort of inherent claim to motivic development. And of course, the possibilities for developing the melody are more numerous than most players (myself included, shamefully) are willing or able to explore in the heat of the moment. Where does further development of melodic cells, contours, or pet licks fit into this picture? For me, it is mostly as a composer and less as an improvisor.