I think this is a really nice idea. I tried ARMS a few days ago and it´s really a fun game. The characters are full of personality and the gameplay sure is addicting. These events will keep people interested. Nintendo should promote more ARMS competitions, because it´s also fun to watch
Hopefully they'll host tournaments outside of Japan as well. They just had a Japan Grand Prix for ARMS. Mr. Yabuki made an appearance in the tournament. Here's the recent livestream.