Lots of people asking "Why?". They say so right on their site: There are big changes happening in the technology industry and they are acting pro-actively to ensure the workers have a strong collective voice in the ways the foundation chooses to respond to those changes.
"The Wikimedia Foundation and the broader technology and nonprofit sectors are navigating a period of significant change. From rapid advances in artificial intelligence to evolving organizational priorities and external pressures, and changing patterns of readership and discovery, the decisions being made today will shape our workplace for years to come. Our union members believe this is the right moment to establish a lasting, legally recognized voice in those conversations. Rather than waiting until difficult decisions are made, we are organizing now to help build a stronger Foundation that can meet future challenges through collaboration, transparency, and shared stewardship."
"The Wikimedia Foundation and the broader technology and nonprofit sectors are navigating a period of significant change. From rapid advances in artificial intelligence to evolving organizational priorities and external pressures, and changing patterns of readership and discovery, the decisions being made today will shape our workplace for years to come. Our union members believe this is the right moment to establish a lasting, legally recognized voice in those conversations. Rather than waiting until difficult decisions are made, we are organizing now to help build a stronger Foundation that can meet future challenges through collaboration, transparency, and shared stewardship."
https://wikiworkersunited.org/faq/