[PeterisP]

While it might have been the intent, that was never a realistic option.

The treaties and decisions of UN can only be binding on the members iff they voluntarily join these treaties. If USSR wasn't admitted to UN, then UN would be even more useless than historically. If UN was designed to be more strict - to require effective, significant delegation/surrender of sovereignty - then even other major powers would not join, and it would also be even more useless than historically.

Theoretically there could be a model of "UN" that would consist of the West trying to impose their decisions on the whole world. But that would require both the will and the ability to actually enforce these decisions despite the cost in blood, and there is neither.

Regarding will, it would have to be sort of like a military aggressive super-NATO - which "the west" was not willing to do; there's a reason why the NATO treaties are strictly as a defensive alliance, and even then limiting the territories which will be defended (so i.e. a military attack on British and French overseas colonies would not trigger any obligations from NATO); and regarding the ability - throughout the Cold War the West was obviously not capable to unilaterally force USSR to do anything, so a super-UN was impossible, and the current UN was the most that was achievable.