Late to the Sith Contrarian Ball

With Tyler Cowen already having made the case against those unaccountable Jedi and (no big surprise here) Jonathan Last offering a defense of Empire on behalf of the Weekly Standard, you'd think the territory here had been sufficiently mined. But I want to toss out something that's been puzzling me since I saw the wretched Attack of the Clones: Are the Republic and the Jedi on the right side of the war? Or, put another way: Why are the Separatists wrong?

Now, we all know the nasty Sith are behind the Separatist movement that launches the war. On the other hand, we also know that their purpose in doing this is to provoke a response from the Republic. And presumably most of the worlds attempting to split off have reasons of their own for wanting to do so, Sith machinations notwithstanding. So what I find myself wondering is, why shouldn't they just let this original "rebel alliance"—the Confederacy of Independent Systems—go their merry way? Far from the Confederacy in this case condoning slavery, it seems to be the worlds of the Republic that are satisfied to at least countenance it. And here's what the official site says about their motives:

Despite rosy recollections of a greater past, the Republic succumbed into undeniable decay. Its cumbersome bureaucracy slowed down any attempts at reform, and too many of its constituents had grown corrupt and complacent to enact any change. A feeling of disenfranchisement grew in the galaxy, particularly in outlying systems where heavy taxation was not balanced by improved services.[…]Count Dooku courted the massive engines of commerce in the galaxy[…]with promises of reform and unyielding devotion to capitalism.

And here's something from the shooting script for Episode II, cut from the final version unless (as is wholly possible) I just nodded out:

COUNT DOOKU: As I explained to you earlier, I'm quite convinced that ten thousand more systems will rally to our cause with your support, gentlemen. And let me remind you of our absolute commitment to capitalism… of the lower taxes, the reduced tariffs, and the eventual abolition of all trade barriers. Signing this treaty will bring you profits beyond your wildest imagination. What we are proposing is completely free trade.

Now, that sounds fine and dandy to me. But even if other worlds aren't down with the program, what justifies forcibly preventing secession? Are we supposed to believe there are some sort of pan-galactic public goods that the republic provides, such that whole star systems are effectively non-excludable? It's pretty much stipulated that many of the outer planets are effectively exploited by the central government. What if they'd just let them go?