There is now a union ... just for Wizards of the Coast employees. UWOTC-CWA now has a monopoly on negotiating for WotC employees. Dues flow up to the CWA, but members don't necessarily get the benefit of bargaining industry-wide. There is also no choice within WotC for what union represents you.

It's still a deeply flawed relationship, especially compared to what a median European enjoys. It's not a simple "US companies bad - EU companies good" - the NLRA is in desperate need of reform by Congress and political actors across the US have stymied progress.

¹ That's union-ize, not un-ionize.

Edit: Words are my own. I am not a rep of WOTC or Hasbro.