Pretty close to my thoughts. I thought things were a lot more interesting and thrilling when there weren't 'antagonists' in the games. These games that are just purely about player versus player violence aren't particularly great. They lack the thriller aspect that the earlier games had where you weren't sure when or how someone might die. Also the fact that we didn't even see how her master lost is pretty stupid given the hype the character had based on game count.
I also didn't see the point in the huge amount of time invested in Moegi if she was going to be so weak. I'm all for building up characters but even with all of her backstory I couldn't bring myself to care about her. It just felt like her existence burnt a lot of time that could have been spent on characters that might be more interesting.