This is a fair point, but the Big 10 has only recently added ice hockey (2014). Minnesota did fine in the WCHA and would continue to perform at a high level without the Big 10.
That’s true, but Big 10 hockey ultimately lead to the demise of the WCHA. Hockey is a big deal in traditional Big 10 territory, especially in Minnesota. They could join the NCHC or CCHA, but that would be considered a step down for the institution (although not a step down in the hockey program).