That argument holds true for a literal florist but as an analogy to filesharing it really breaks down pretty quickly, after all the garden would never empty of flowers 'taken' if they were copied. Your argument below that they are not 'free' because they take up server space and electricity and so on are also not valid because the storage, electricity and server space is not exactly provided by the original authors in the case of a pirated copy.
The whole piracy thing is a backlash against people that have been stealing from artists and consumers both.
Go read Janis Ians writing on this, or Courtney Love, or countless of other artists that have spoken up about this.
Times are changing, we'll find a new equilibrium and those that had a free ride for a long time will have to find a different racket at some point. Technically speaking they're already dead.
It will just take a while longer before we get there.
Artists that make music for the love of their work will continue to do so, and will find a way to make money. Artists that are creations of the media machine will have a problem, but then again, most of them weren't in it for the art to begin with so there is probably not much lost there.
I can't even name one band launched in the last 5 years that stood out for me that was not an indie band.