Band in a Box to an arranger, is like a Workstation to an arranger, in that there are many overlaps, but they are designed for different jobs.
Band in a Box:
Great for projects, waste of time for on the fly backing.
Workstation:
Great for voice manipulation and real time control, waste of time for making and using styles.
Arranger:
Great easy play features and backing for OMB waste of time for any serious project work due their inflexibility.
Programmable real time control and easy operation of advanced editing is a must for project work, as is a highly flexible (And predictable) backing track creator. (A limited NTT (As in an arranger) is of no use whatsoever)
Bill
Biabox, or an arranger with chordsequencer are also a very welcome tool for people playing their piano lessons that want a fun backing, it just takes half a minute to create a bakcing ..
Also for singers, its a great tool.
Same goes for guitarists, works much better for guitarists then an arranger.
While i agree mostly with your opinion, its very obvious the opinion of a pro and gigging musician... In the end however, it is nice to have all these 3 in a single setup.. All for their own reasons.