World wars are uncommon whether we have nuclear deterrents or not, after all we had none before 1914. However we have had major near decade long regional conflicts and many wars by proxy between nuclear powers. While it's persuasive to think that nuclear weapons have prevented world wars, there isn't much evidence to support that idea.

While it is true that there weren't any wars called World Wars before 1914, what really distinguished those wars was the weapons technology and the massive devastation that resulted from that. Human nature does not change as quickly as technology does, though, and if you define a world war as a war that involved all the major powers of the time, there were in fact four wars in Europe before that that involved all the great powers of the time in two rival alliances: the Thirty Years War, the War of the Spanish Succession, the Seven Years War of 1756-63, and the Revolutionary and Napoleonic Wars.

With that in mind, that makes world wars considerably more commonplace. Given the timing between the six world wars, we're in a definite lull. Nuclear deterrence is likely the major reason for that.

In terms of "massive devastation", scaled for population, I strongly suspect the Thirty Years War will give either World Wars a run for their money in the area over which they were fought. It certainly left very deep scars that were felt up to WWII....

Echoing your point, the Napoleonic Wars ended 99 years before the start of WWI: https://en.wikipedia.org/wiki/Battle_of_Waterloo The precursor wars which very much were an input into WWI ended less than 45 years before: https://en.wikipedia.org/wiki/Franco-Prussian_War (and I'm in the camp that primarily blames France for initiating WWI).

There's a big difference between wars conducted directly by major world powers and little conflicts by proxy. They are not the same thing especially when it comes to scale. The other replies to your post have already made my point.