system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU]Why is Thor the only asgardian to come after Loki?

Thor isn't the only powerful Asgardian, and it would be boring if he was. He's also the crown prince, so it can't just be "a family squabble." So what does that leave you with? A test to see if the humans can handle it? With a lot of collateral damage.
gpt
In Avengers? Asgard hadn't rebuilt the Bifrost yet, and so Odin needed to rely on other magical means to transport Thor to Midgard. Sending Thor in this manner took a lot of energy, and so no one else could be sent with him (at least in a reasonable time frame).