Look, I consult on enterprise level technology decisions for a living. If a customer asked me whether he should root his phone to enable wireless wifi tethering, for example, I would strongly advise against it unless it didn't matter whether it worked or not. Likewise, if a customer asked if he/she should allow his/her employees to overclock their Droids to improve performance I'd advise against it. Just as I'd advise a client using pirated Microsoft Office software to get rid of it.
In each case, these actions involve both legal and technical risks, not to mention increased costs to monitor, track, and fix problems. None of these factors impact the average hacker. They all impact a user for whom time is money and risk mitigation is important.
I'm not sure what you are getting at. What does this have to do with root? If you root your phone, you can unroot it if a situation occurs where you need developer support. There are roms out there that have zero support, I mean, look at Adamz roms for a few months there when he dissapeared. He was completely MIA and it didn't matter as far as functionality was concerned for all his users. Not one bit. What did rooting have to do with any applications we were using?
There are thousands of people with "issues" but there are plenty of them with unrooted phones also. Most issues are found and addressed right away.
Your examples above are completely right, but you are in a much different situation. If I worked for a company and they issued my Droid to me for email and work purposes, I wouldn't even THINK about rooting it. But that isn't MY device. Just like I wouldn't put new speakers into a company car. But I sure as hell would in my car, and I sure would with my phone.
The point I'm making is that I wouldn't want someone to read your post and think they shouldn't root. I rely on my phone, I use it to log into my work email if needed, my office phone forwards to my Droid. I use it for multiple purposes, and never once has rooting ever cause one issue with email or web browsing, the two things I *need* for work.
Bottom line is rooting has been nothing but a way to get more options. As long as the device belongs to you, go for it. You can always revert back if needed.