Having hung out recently with about a dozen low budget guys here in LA, (who do lots of shorts, ultra low-budget features, student films, etc), the Spitfire stuff is perfect for them, especially anything with "Hans Zimmer" in the branding.
Most of them come from pop/rock mid-2000s or late-90s bands and have no real knowledge of how an orchestra works. If you show them a picture of an english horn and ask them to identify if it is a single reed or a double reed, they'll ask "what do you mean? Like, how does this instrument read?"
The Spitfire stuff is good for them because they can play block chords of vi - IV - I - V, slap on some takio drums in a 3-3-2 rhythmic grouping, and it sounds "cinematic" to a client who doesn't know any better.
VSL on the otherhand is for composers who need a tool that has a extensive expressive range. I foolishly bought the Spitfire Symphonic Brass a couple years and absolutely hate it now that I know what I'm doing with sample libraries. When I tested it and could play the horn solo in Till Eulenspiegel. Months later I tried to play Petrushka with the trumpet and it's simply not possible. Most things in the brass literature are not possible with Spitfire.
With the exception of works requiring extended techniques, the Synchron series has yet to show me that it isn't capable of rendering any passage from the classical repertoire. I believe it engenders composers to rise to the challenge of being able to make use of that full expressive range. Technology is leading the way, artistically, so far this millennium, and it is a benefit to us all.