Yeh, quick test:
How many of you defending the use of Boys would be happy if we replaced it with Girls? Be honest.
You know how many times I've been in a group of males and someone referred to us as "girls"? Probably dozens of times in my life. Not that these are the same thing, because clearly the people doing so are intentionally flipping it to try to be funny (whether they are or aren't). In fact, in that case, it's meant to be offensive (or ribbing, whatever). Again, I'm not comparing the two situations at all, but it is a fact.
In the cases you state, it is in no way shape or form intended to be hurtful. That's the big problem I have with this.
When I was a kid, I said "that's gay" allllll the time. I called people "fags" allllll the time. Not because I disliked homosexuals. I never really gave them much thought one way or another. It was because at the time, those words meant "bad". I stopped saying those things because I realized it wasn't right. Those words are hate speech derived from decades of homophobia and the hating of homosexuals. I didn't and don't hate homosexuals, so I stopped saying those things. I broke the habit. I realized I most likely said it within earshot of a gay man or woman several times, and I felt awful thinking about that.
There have been many times in my life where I have been in a group of people, and knew someone in that group that was homosexual, and someone from outside the group would say "that's gay" and I would feel really embarrassed, even if I didn't know either person that well. I knew it struck a negative chord with that person. Even if it wasn't meant to be harmful. It struck the chord all the same.
The problem I have with this whole "boys" thing, is that it simply doesn't have the history that those other words do. It doesn't have the hate behind it that they do.
If someone in my group told me to stop saying boys (as I said in other post, I don't actually say "boys" very often, but "guys") because it made them feel uncomfortable, then I would absolutely do so.
The difference is, this is a message board with thousands of people.