It would be really irritating for many people; that behavior is best left to the user and the browser (most mice have middle-click which opens a link in a new tab, and - on my laptop, at least - tapping with two fingers opens a link in a new tab. Browsers can also be configured to open off-site links in new tabs).
I just find it irritating when I forget to ctrl-click and having to refresh the HN page. Posted stories are not necessarily in same order. Maybe it's just me :/
That's just you. I perhaps find it equally irritating when I click a link and it goes to a new tab.
If I wanted it to go to a new tab, I'd have CTRL+clicked.
*Edit -- "That's just you" is definitely too harsh a statement, as I'm sure there are a ton of people that agree with you -- That said, I don't see a compelling reason to futz around with default browser behavior unnecessarily, and I'd wager that doing so is considered bad UI.
Should be expected according to who? Reddit doesn't have it, CNN doesn't, slashdot doesn't. Web IRCs do, but for good reason, it automatically logs the person out of IRC.
If I wanted to open the website in a new tab, I press Control+Click.