Management is already fighting employees. The difference is, management bargains collectively, and employees do not.
For anyone who thinks that they have a strong bargaining position, or enjoy great perks: Try asking for an escape from the open-office-floor-plan-hell, by getting your own office. You'll quickly see exactly how valued your special snowflake concerns are to the company.
That, I see as a bad example of needing a union for depending on what the company is preferring the open-office floor-plan for. I think it makes sense for a company to optimize on real-estate costs to run a viable business. After-all they aren't forcing you to work there.
I see unions as a way to protect employees from being unfairly taken advantage of (long hours without commensurate benefits and choice on your part, dangerous working conditions, bad salaries/wages). A bad office design is a bad office design and you need to convince your company that it's not in their best interests by other means or work elsewhere. Using a union to deal with all this will only end up in causing bad-blood all around. For certain things legislation is better -- you can blame the "government" boogeyman instead of being pissed with each other.
For anyone who thinks that they have a strong bargaining position, or enjoy great perks: Try asking for an escape from the open-office-floor-plan-hell, by getting your own office. You'll quickly see exactly how valued your special snowflake concerns are to the company.