A few months ago I asked you why you don't do remote work. I followed up with an email. I realize you're busy, but still I would have appreciated an answer, since you asked me to send you an email anyway.
We're an office culture. We're constantly getting into situations where we hit technical challenges we haven't solved before, but someone else in the office has. Several times a day you'll see people crowd around someone's computer trying to work through some bug or misbehavior to see if we can, as a group, turn it into something exploitable. That's reason #1.
Reason #2 is fairness. Some of our work is on-site. We arrange our offices so that we have "house accounts" in Chicago, NYC, and SFBA, and on any given day some fraction of the office is likely to be at one of those places. All things being equal, people would like to work from their own office instead of someone else's. If we pick up remote people, those people will by definition not be able to staff on-site projects, which mean that the people who actually come to the office will get stuck with that work.
Reason #3 is that reasons #1 and #2 have been dispositive for us since 2005, and so we have a management structure tuned to that office culture. We're not set up to manage remote team members. We're especially concerned about this because some of us have experience working on assessment teams at "work from home" firms, and have seen wildly uneven results from projects managed like that. We're paranoid about quality and consistency the way a fine dining restaurant is paranoid about the consistency of dishes coming out of the kitchen.
I'm not saying that there's necessarily anything bad about remote/WFH cultures, or that you couldn't build a good assessment firm doing remote/WFH. I'm just saying we haven't done it. :)