And all of those arguments are silly, because the only barrier is the level of abstraction. There's nothing more pathetic than seeing a good suggestion getting swamped by people who nay-say on a gaming forum for a living. I've never seen such knee-jerking.
Calling it 'knee-jerking' doesn't make it so. What I see is that some people want World War I games that focus on the era World War I happened in, rather than tacking that entire era onto the few which preceded it. EU4 already covers a vast range of eras. The industrial era, with the first world war that followed it and all, should be handled with its own mechanics. We shouldn't need to fight a war in the 20th century with the game designed to emulate no further than the 18th century. That's a good thing - if I were to play a World War I game, I'd want it to feel like World War I, not the War of the Spanish Succession - which is what would definitely happen if we extended EU4 to cover WWI. Its how EU3 covered the Napoleonic Wars and all, and they never felt right from my perspective.
And that's before we look at the entire goddamn nineteenth century - the 'we already have a game for that' argument is readily apparent. If you don't want to play Victoria 2, you're not going to bloody find a better game covering that era of industrialization and nationalism, imperialism and revolution, so a bloated EU4 stretched that far can only be worse than the polished political-economic jewel that is Victoria.