As long as Plus is sold as 'beta' or whatever, there is no real risk to opening it up to App accounts - regardless of whether they are personal users or enterprise users - because it's a conscious opt-in process being made by technically literate administrators.
And as many of others have already said, there is a big downside to treating your App administrators as second class citizens who can't make their own decisions - you lose the very people who have an appetite to try new things (why else did they move to Apps instead of using MS Office or whatever), and who are generally drinking the Google Kool-Aid. It's probably not the best analogy, but I think it's like Apple releasing the iphone 5 and saying 'Anyone who bought a previous iphone within 30 days of when it was released is not allowed to buy the new iphone 5'.
They can't just enable G+ for the sake of trial, when every employee must be trained for the application.
2: While Google+ appears to compete primarily with facebook, it also had the chance to cement the business market early on. Salesforce and others have been aggressive in pursuing this (chatter, et al). Would/will be a big differentiator for Google.
3. Additionally, apps wasn't always so aggressively positioned for just business and personal use. Early on it was very poorly positioned (looking back at some of the early how-to posts shows lots of "what exactly is google apps for your domain" type posts). There were certainly many, many power users that signed up in those days before it became clear just how poorly coordinated service rollout was between google and google apps.
4. Finally, regardless of what Google Apps is "meant for", what it is "used for" includes lots of users that are, indeed, excellent beta testers.
Are you kidding? You do't even get a "fat packet" when you sign a company with 95 employees. I got an email. Which had a link to log into the Admin account.
I had to write up training materials and provide them to the other employees. And don't tell me, all the docs are online. They'd (the employees) would never browse them. They too busy.
Google does a horrible job in this regard.
I got Microsoft knocking on my door this week. Trying to convince me to switch us to their cloud. They'll provide all the retraining and support. But they also trying to push Windows Server on me. So Google is lucky. :)
As you say, the core use case for Google Apps is for an enterprise, university, or some other kind of organization to give accounts to users that are managed on their behalf. In essence, all of the accounts are owned by the organization, not the user. Now, what happens when the organization revokes your account, because you graduate? The idea that that is possible is absurd.
(In case anyone reading doesn't see what I mean yet, imagine if Facebook locked you out of your account when your University cancelled your e-mail address after graduation, instead of just letting you associate a new one; your Google Apps account isn't just an account associated with an address at a domain, it is an account that is equivalent to an address at a domain.)
They really need to decouple a Google account from a person's email address(s).
Exactly. In fact, one should be able to "attach" multiple email accounts to a single Profile.