Thanks for pointing this out. It was fun though not a huge deal to me. If they add other free "live" events, I'll participate but if it turns into English languages concerts, I'll be a bit weirded out. If they charge to attend or some other micro-transactions, I'll be out as well.
If it is teasing a bands pack, I'm probably interested, it just depends. If I am just not interested in the artists, I'll probably ignore it. I'm on the fence about any live event based challenges and would only do them if they are free and interesting to me.
They essentially need to keep the sandbox aspect while giving challenges to those needing them. Part of me is having fun but if it gets too commercialized, I might drop out. The free concert was a fun move. It doesn't mean that I'd go for everything.