Strikes are so 20th century. We're not talking about 9 year-olds working in coal mines here, folks.
As for something positive to say about unions? They have a purpose as a collective bargaining unit, negotiating pay and benefits for a large group of employees. That's about it.
I think you're taking far too narrow a view.
Unions have a purpose, as part of a system of checks and balances that ensures business doesn't take too much advantage of labor. We're not talking about 9 year olds working in coal mines
here. A big part of what's hurt the power of unions here is that business discovered that they can be more profitable having their work done by the non-unionized workforce in less developed parts of the world. I believe I've said it before--American labor would be helped immeasurably; American unions would be that much more relevant, if some union would go and organize a few billion Chinese.
And further, about 9 year olds in coal mines, some will make the argument that unions have outlived their usefulness because we now enjoy the protection of laws that prevent that sort of abuse, and much more. That's certainly true, but I don't think you can discount the voting power of organized labor in attaining those improvements. It follows then, that the voting power of organized labor is a force to protect and maintain those improvements. One need only look as far as the clothes on retailers' shelves to see that kids in sweatshops are not beyond the moral limits of business. It may not happen on our shores any more, but it still goes on, and it's on sale now, just in time for Christmas.
Is there a way that we could maintain this capability (which seems like a valid one) without the threat of strikes?
No.
One need only look as far as NATCA, and its predecessor PATCO, for an answer to the usefulness of strikes. The issues that are most troubling to today's ATC workforce are nearly identical to those that the ATC workforce faced in 1981.
An (perhaps overly long), essay on the subject:
http://etext.virginia.edu/journals/EH/EH37/Pels.html