I don't think it is childish or off the topic at all to think about the meaning of samplers to composers. It is the most important thing in a way. I think the great composers of the past would have gone APE with the Vienna Symphonic Library! One thing I have always noticed is that music is considered almost always from the standpoint of performers and NOT composers. The conclusion has often been that samplers were to be frowned upon because they put performers out of work.
Of course, many performers have gotten work BECAUSE of sampling technology, whether by recording samples, or by playing solos with otherwise sampled recordings.
But all of that is beside the point in a way, because from the standpoint of a composer, this is the greatest development in the history of music. For the first time an individual has the ability to write with sound itself, instead of with only the symbols for sounds.
That is a fascinating story about the old professor, and very significant too, because it shows that samplers are not merely a crutch or a substitute, but a tremendous tool in themselves that allow a composer or orchestrator to perfect a musical idea in actual sound. Not for selling, or substituting, or cheapening the process, but for pure artistic expression. The amount of control one now has, especially with the level VSL is on, is beyond what most conductors ever have, given the fact that rehearsal time is so short, and the performers in a live orchestra are not always in tune, expressive, or even on the right pitch! Having been a professional player in orchestras and bands, I know this from painful experience.
Also, I think it is important to remember that most orchestras are not like the London Symphony, the Philadelphia Orchestra or the Berlin Philharmonic. A composer is much more likely to get a local group or a student orchestra to play his music, unless he has reached the pinnacle of success (and is probably at least 80 years old.)
Sorry to go on and on but I think the sampler is potentially a great musical instrument in itself - very demanding, complex and expressively beautiful, and deserving of serious artistic status as well as commercial value.