Here's the issue with that. Yes, I can FORCE it for everyone, but if I force it, users don't have the "either/or" choice. I try to follow W3C guidelines, which is to not open the links in new windows unless they are for instructions, etc. When I don't force that setting, you have the option to just right-click and "open in new tab/window" if that's your preference.
Like you, I prefer they open in new tabs for outside links, but I also realize that not everyone is that way and decided not to force that setting.
Since I did make this entire site secure via SSL cert, it's easier to justify that since external sites opening in the same window would break that encryption anyway.
So what I will do is to take a middle road and set it up so that users can enable/disable "external links opening in new windows" in their control panel on the site based on their own preference.
I already coded the control panel for that, but just need to set up the code and test.
Same answer applies to notifications. You'd be surprised how many complaints I used to get of "spamming" users with email notifications when I had it enabled by default. I figure it's best to leave it off by default and let users enable it if they prefer.
Longer answer than you wanted, I'm sure.