Agreed, and some of them are a perfect demonstration of how Reach has taken a step backwards.
Personally, I hate playing with or against guests. If you want to invite some friends over to play Halo split screen that's cool, I just don't get matched up with your party because it unbalances the game in most cases. Block them from certain playlists, match them up together, I don't care as long as I don't play them.
Previous games used to match you up with other parties (3+1 would play with other teams of 3+1, same with parties of 4 etc.) Why this was removed for Reach, I have no idea.
I always preferred ranked matches in earlier titles. For all Bungie's insistence that Trueskill (and ELO/Levels in H2) operated in 'unranked' playlists it's obvious that the skill matching is broad at best, non-existent at worst. Once upon a time when I was playing at around the level 50 mark in H3 Team Slayer, despite the wait times for matches it gave a consistent and challenging experience. In Reach it's all over the place. One game I'll be with a team that crushes the competition, the next it'll be reversed.
As I said a few days ago, I think Halo would be far better if it moved back from Trueskill to ELO a la H2. It's much simpler so it can be tweaked much more easily without requiring a degree in mathematics to avoid breaking it, and ELO didn't have half the bugs and general weirdness I experienced with H3's Trueskill.