The creation of the Commonwealth of Independent States was a tactical move to preempt a similar initiative on the part of Gorbachev. It was also an attempt to counter the model of the USSR's Stalinist leadership under Gorbachev with a post-Stalinist paradigm of collective leadership.
This solution was attempted before, in the wake of Stalin's death in 1953, but only at the Politburo level. In 1991, Russian republican leader Boris Yeltsin contrived a variation of the plan by plotting with his counterparts at the republican level. It would be a republican collective leadership, circumventing the Politburo. Yeltsin invited his Ukrainian and Belarusian comrades to outmaneuver the General Secretary of the CPSU by establishing a collective leadership of the Soviet Union, now renamed the CIS. It was a plot against Gorbachev and the Politburo, but not against the USSR per se.
With the benefit of hindsight, it is perhaps natural to credit Yeltisn and other comrades with introducing state sovereignty of Russia and other republics under the guise of the CIS. However, initially at least, they intended neither to destroy the USSR nor to champion secessionism of the republics. Instead, they followed the Soviet succession struggle model with which they were very familiar. Eventually, they ran out of their Leninist moves; the utility of the paradigm ended. Instead of being the final solution to chaos in the USSR, the CIS proved to be an unworkable stop gap measure, a half way house.
Thus, the collective republican leaders, undoubtedly surprised, took the logical step of emancipating themselves from the framework of the USSR. It took some time to conceptualize life outside of the Leninist box. When it did happen, the participants, observers, and scholars reflexively and deterministically adjusted the outcome to fit their pre-conceived notion of Yeltsin's alleged intentions.
It is usually ignored that the final implosion of the USSR was a case of the law of unintended consequences resulting from the Leninist tactics at the center. This is phenomenon is generally misunderstood by scholars and contemporaries. Gorbachov's take on this is very revealing. He casts himself as the proper Leninist centrist: between the "reactionaries" of Gennady Yanayev and the secessionists of Boris Yeltsin.
In fact, all parties involved wanted to save the USSR with the Russian Soviet Socialist Republic as its pivot, but they advocated competing visions. Gorbachev wanted a Union Treaty which provided for a confederative structure: The Union of Sovereign Nations. Yeltsin wanted the same, but without Gorbachev and other top people in the Politburo. Instead, he championed parallel structures between the republican leaderships to circumvent and replace the old center. Yanavyev and his comrades wanted to save the USSR in its unadulterated Stalinist glory. Thus, they carried out a failed palace revolution against Gorbachev. Neither of the leaders had a strategic vision of anything beyond the familiar framework of the USSR.
Ultimately, however, Yeltsin fell victim to his own Leninist tactics of outmaneuvering his opponents and pushed his concept too far to continue accommodating the old Soviet paradigm. Thus, the center failed to hold. As Gorbachov himself put it:
Participants in the [Yanayev] conspiracy said, and some still say, that they wanted to save our union [the USSR]. But, as I said from the start, they ended up destroying the country. Although the coup collapsed three days later, it damaged the principle of a common state, speeding the republics' ‘run on the Union' - a process that Russia's leaders had initiated long before the putsch. One after another, the republics began declaring independence. The situation we faced was indeed grave. But we were able to convene the congress of People's Deputies, which approved preparation of another draft of the Union Treaty, based on the concept of a confederative state. We ran into all kinds of problems, but we soon had a new draft and began presenting it to the republics. Once again, the prospect existed that we could work together to end the crisis. Had it not been for the collusion of the leaders of Russia, Ukraine and Belarus, meeting at Belovezhskaya Puschcha, the new treaty could have been signed before the end of 1991. The union, which would have been known as the Union of Sovereign States, would have been saved - in a different form, and with much greater rights to the republics. Had that happened, I am convinced that economic reforms would then have been less painful, the collapse of industrial production would have been avoided and the dangerous decline in Russians' living standards would not have occurred.1