Although I frequently disagree with Dr. Crazy, I have to give her props on this post. There's something anachronistic about the way most colleges do 'office hours' at this point, and we need to rethink them.
The traditional version of office hours has professors post a set number of hours per week that they'll be sitting in their offices, available for students who need them. The required number of hours varies; for full-time faculty, I've seen everything from a low of three to a high of fifteen hours a week, depending on the institution. (Typically, adjuncts are not required to hold any.) I'll admit staring in slack-jawed disbelief at fifteen, but it's out there.
In the days before email, office hours made a fair degree of sense. Students who needed to speak with their professors outside of class had at least a fighting shot at finding them at a given time and place, and they could make appointments accordingly. Yes, there were always schedule conflicts, and yes, some faculty abused the freedom of scheduling by deliberately scheduling times when they knew nobody would look for them. (8 a.m. on Monday? Really?) But in the absence of reliable asynchronous-but-quick communication, it was often the best that could be done.
Now, of course, a great deal of student-professor interaction occurs electronically. Depending on local rules -- most certainly including union contracts -- this kind of interaction may or may not 'count' toward the office hour requirement. To the extent that it doesn't count, professors who are conscientious about maintaining online availability at given times rightly chafe at what they perceive, more or less correctly, as extra unpaid work. (I'd draw a distinction between "maintaining online availability consistently at given times" and "answering the occasional stray email." The former looks like an office hour to me; the latter is just basic professionalism.)
That said, it isn't as easy as just tossing out the concept of office hours. (To her credit, Dr. Crazy acknowledges this.) In a system in which students are required to have academic advisement, it isn't unusual for students to just drop by departments looking for someone to talk to. In the complete absence of in-person office hours, scheduling appointments becomes a labor-intensive crapshoot. With at least some regularly-scheduled time, it's easier for students to know when to look. Although electronic communication is great, some students still prefer face-to-face conversations, at least some of the time. It's a fair expectation, and maintaining at least a minimal level of scheduled availability allows for that.
There's also the issue of college service. In theory, of course, there's nothing stopping professors from coming to campus on days when they don't have classes or scheduled office hours, and some do. But experience has taught me that a non-trivial number of people will minimize their number of days on campus per week, then used jam-packed days as excuses to avoid any and all college service. I've seen it happen enough times to appreciate the value in just ensuring that people are physically present a certain amount of time. When half the department shirks service, the other half typically picks up (most of) the slack, completely uncompensated. And I've heard "I'm not driving to campus just for a meeting" enough times not to discount it. There's a reason that the phrase 'full-time' specifically references 'time.' Some elements of the job can't be done from afar, so a too-quick abandonment of office hours would dump those elements entirely on an unlucky few.
Wise and worldly readers, I suspect that this issue varies by context more than most. Has your campus found a reasonable way to revisit the question of office hours in light of electronic communication?