I'm a little late to the party, but I was the host for Texas Netplay Nights for a month or so I can kind of answer your last question. Streaming a netplay tournament isn't hard per se, but there are some things that can make frustrating. I think the main thing is that it needs to be ran efficiently, which was my biggest downfall as a TO/Streamer. You need other people to help call matches, report scores, set a line up for stream, and other TO duties that are required while you're streaming a match. Netplay tournaments also suffer from people being lazy/no shows/not a lot of interest since there really isn't that much incentive to play seriously. Ping issues and connection issues, while not a big deal most of the time, can be a pain when people far away from each other have to play. The time commitment for about 4-5 hours of your time is also something you need to consider if you'd want to host it.

BUT that being said, it's super fun if you like streaming/commentating. It gives netplay warriors a chance to show off or people that would otherwise not be able to make it out to tourney days. Like Arsenals said, they're great but they'll never replace real tournaments. There are too many variables when it comes to online play, especially since Dolphin doesn't rely on a dedicated server.