To play devil's advocate for a moment, we should also remember that sometimes (not always, but sometimes) people
do have a choice in what they're offended by, and how they react to those feelings of offence. A lot of the people in this thread aren't even saying that they find it offensive personally, but that they feel that they
ought to find it offensive on behalf of other people, which is very much a conscious decision on their part. If you react to the mere fact that some people complain about something without considering whether they might be wrong, you'll self-censor unnecessarily. And that makes it more difficult for others to resist self-censorship later.
The thing is, I don't think 'bro pages' are offensive. More than that, I don't think that they should be offensive. Are we seriously saying that we should attempt to avoid using any words, even in metaphors or puns, that might ever remind someone of a person stereotypically assumed to be annoying? Really? This feels like linguistic bikeshedding from people who, having realised that words have the power to offend, have set out to find offence where not only was none intended but where it could only be found by actively construing the speech as offensive. It's a massive piece of WWIC[1], driven by an attempt to appear more sophisticated and culturally aware, which massively exaggerates the potential harm caused in order to make a case that someone else (but never the critic) should have behaved differently. Instead of accepting that no harm was meant, and acknowledging their own free choice to decide whether to interpret something as harmful, they're claiming that the words they see are simply inherently wrong and must be changed.
Now, I should attach some massive caveats to the above. Some speech is inherently offensive. We know it's offensive because we can all close our eyes and imagine the worst things we could say to someone. There's almost no innocent use of such speech, although context, intent and consent are important. Such speech has no place in civilized discourse and HN is, for the most part, civilized discourse. 'Bro' is not such speech. 'Bro' can be amusing, annoying or neutral. It can make people smile, frown or feel indifferent, as can many other words in the dictionary. Naming things[2] is hard enough without the restriction that the name can never, ever, be interpreted negatively by someone trying very hard to do so.
[1] http://www.ftrain.com/wwic.html
[2] http://martinfowler.com/bliki/TwoHardThings.html