Sorry, Kirk, I'm an architect, not a chippy, though that's by no means reflects on sound advice from chippies.. The diagonal bracing is easy and cheap to apply and good insurance to prevent drywall joints opening up in case the wall experiences some movement, especially around door openings, if any. otherwise I would agree with you, it's overkill.
I guess one question that nobody has asked is what is going to be the framing for the wall? Will it be lumber for the studs or will they be metal studs? I would guess that since it is a commercial application they will probably be metal.
You might want to consider adding at several places along the wall a conduit extending down from the top to a 4x4 outlet box for future use. This makes it *real* easy to add speaker wire, network cabling, video hookups, etc., later when and if needed. (Or power, for that matter...)
The outlet boxes can have blank cover plates until you need them. This is especially handy if the walls will be insulated for noise, etc. And EMT and 4x4 boxes are pretty low cost.
I installed several along selected walls of my living room, office, and bedrooms during construction. One of my better ideas...