Yes - I agree. This is a tough question. If it is just a casual group of non-Japanese friends chatting about games, why inject a hierarchy into this which will forever make the youngest person feel like he/she has to defer to the sensibilities of the senior members? Plus it has the reverse effect of entitling the senior members to feel offended if the youngest person hasn't used the most appropriate and deferential language.
On the other hand, if the hierarchy already exists and the group wishes for a formality expressed in language, you could well argue that dropping the gozaimasu injects an unwelcome familiarity into the conversation.
If you are a group of friends, though, and wish to remain casual and friendly, you should overlook such trivialities. Otherwise you are forever arguing that so-and-so used "kimi" when he should have instead used "anata", etc...
The answer is therefore: are you a group of people that values the hierarchy more than the friendship? If so, the omission of gozaimasu would ruffle feathers. If you are a group of friends; friends don't always demand formality from other friends, and so it may go unnoticed.