An unexpectedly strong negative response. You're looking at this from only one perspective.
Would you call a friend a selfish ass for asking you to wait 45 seconds before starting while they run to the bathroom? If the answer is no, then you have no right to say I'm a selfish ass for requesting this feature, because it's essentially the same thing except it doesn't require you to delay the other people.
Secondly, game rooms are not public facilities. They operate at the sole discretion of whoever is hosting. You don't have the right to be in their game just because you want to be; they can kick you whenever they want. I see people kick others from rooms all the time because they don't want to wait on a download. If anything is poor etiquette, it's this. There's currently nothing you can do about it. This is not meant to address that problem either, I'm just pointing it out.
Instead of only looking at the negatives, try looking at the positives and see if the potential benefit outweighs the potential so-called abuse.
The entire point of this is to be courteous to the people you're playing with. You have no obligation to be courteous to people who aren't even in your game, and potentially don't even exist in the first place.
Here's another possibility: make the feature only apply to locked rooms. This could be mainly for usage when you are playing with friends, and don't want to hold them up. Yes, it could be abused in unlocked rooms easily by telling people to skip whenever they have to download. This is an obvious downside and I'm not overlooking it (although you two did, instead focusing solely on it being "bad-mannered" when in fact it is the opposite.) If there's a solution to that problem then it would be very usable in unlocked rooms as well (which would make it a lot more useful; there's little point for it in a locked room unless it's a semi-public locked room). I can't think of one at the moment, but that's what discussion is for.
If you think this is a bad idea in the first place, you don't have to come in here and essentially "shitpost" the thread. If nobody supports the idea then it obviously won't be implemented. Name-calling doesn't accomplish anything either. I see a lot of overbearingly negative posts on this forum, and it's likely discouraging people who actually have good ideas from posting them.
I'd like to hear ideas on how to prevent hosts from abusing this in unlocked games, because that's the only downside I currently see. A limit is one viable option, say one skip per 30 minutes. I probably won't be defending the basic idea anymore; this post should be sufficient for that. What I want to see in the rest of the thread is either pointing out flaws that need addressing (such as the abuse by a host that I brought up), or ideas for improvement. If you plan on posting a stream of insults and not contributing at all to the idea, please just move on to the next thread on the forum.