My status as an administrator doesn't make my opinions any better or worse than anyone else's.
The new-app-in-Dock issue is definitely not a "big deal" to me, and of course takes only a split second to change if I don't like it. My comment is based on a principle, not a problem I care much about. The principle is that applications should not make changes in your settings unless they need to, or at least without giving you a choice.
Perhaps a better example would be if you invoked a web browser you wanted to try out and it changed your settings to become your default web browser without asking you. That's a case where I would expect most users to find fault with the software, based on the same principle.
Here's another case: I've installed StuffIt, many dozens of times, on computers at the school where I help out. Every time I install it, it puts an alias of itself on the desktop, and I routinely delete it. It's guessing that I'd like to have the alias, and it's guessing wrong.
The author of an application is likely to have an inflated opinion of the application's importance, which is why I think they tend to assume you'll find their application important enough to keep aliases in your Dock, on your Desktop, or elsewhere. It's true for a few of them, but I should be deciding this, not them.