Rimokatolik wrote: there is still range of sound that orchestra can product that pipe organ cannot. Well, pipe organ will never be able, but digital organ and especially VPO (in our interest) can.
Yes, but as Martin explained, HW (and other Virtual Pipe Organ software) is specifically written and optimised to reproduce Pipe Organs.
In particular, the basic 'tone' of a pipe is reproduced. There are some more subtle effects such as a choice of attack and release sample that more accurately represent the real behaviour of organ pipes, but the reality is that once the pipe has 'settled down' the tone is effectively constant.
Orchestral instruments, especially strings but also other instruments, are much more expressive (not to be confused with 'expression' in the organ specific sense. By this I mean that a cellist, for example, can and will change the tone, loudness and possibly pitch of a single note, while it is playing, in a variety of interesting and subtle ways by altering the bowing, finger position and so on to suit what he or she (and possibly the composer and/or conductor as well) thinks best. None if this can be accurately reproduced in a real pipe organ or VPO.
And then there is pizzicato playing.
The point is that the realistic reproduction of orchestral instruments involves a fundamentally different set of tone-production and control problems from those of pipe organs.
It is true that one could, and people have, recorded single tones from orchestral instruments which can be played back, faithfully, from a keyboard but they just won't sound convincing (or even particularly interesting) in my opinion.
Nick