Ross,
I totally disagree with you on just about every point that you list. And my experience is that your conclusions are inconsistent with what actually occurs at customer sites, and I've been doing Exchange and Exchange consulting for over 10 years now.
The statement of not being able to manage an environment without quotas is just wrong. Want an example of how an environment with a ridiculously high limit can work? Take a look at your buddies over at MSN or Google with 2GB FREE mailboxes. I'll guarantee you that they know the details of users and servers more than 99% of the mail installations. You seem to subscribe to the belief that "if you provide it, they will use it" That's absolutely incorrect, otherwise all of these MSN and Google mailboxes will be full, and if I remember rumors correctly, they AVERAGE less than 25MB per user.
For a standard corporate environment, you can pretty well assume that the average usage will be in the 100-200MB per user range (dependent on the type of organization). From that you can easily extrapolate the server sizing needed for an organization. Limits are limits and are very different from averages. Averages are what system sizing should be based on, not limits.
And as part of mailbox etiquette you indicate that users shouldn't use email as a file storage facility and that other solutions such as SharePoint should be utilized. Well, first of all, remember IT is a SUPPORT organization and that IT should SUPPORT what the users need. but more importantly, let's just take the situation where you and me want to do a little business and exchange some files. How long would it take for you to get a SharePoint portal created and accounts for me created and the files uploaded? And then what mechanism is there that would make sure that the site is deleted when we finish corresponding? I know that in probably 99% of the organizations, this isn't only hard, it is impossible for a standard user to request!
Exchange actually provides one of the best solutions for file management that Microsoft currently has. What other solutions allow me to share files with ANYONE on the Internet at ANY TIME with no prior setup? What other application allows me to replicate that data between my server, desktop, and laptop and even access the data with an Internet browser?