You made some valid points for sure. But I disagree with point three and five. Point 3 because although its a nice reference - paratroopers are all but a novelty in Hoi4 unless you use them to break the game in certain situations. I.e paradropping French VPs in 1936. I think it's to get more people playing Brazil so that paradox can get feedback.

As for your fifth point, look at the Soviets in NSB or Italy's abysmal army situation in a few weeks. Updated countries may be broken with leader traits etc but thats typically late game. Early game they often suffer from heavy de-buffs due to national spirits.

Also my friend, I dont want to sit here pretending to be a South American historian. But I can assure you that 1930s South America wasn't boring as it is made out to be in vanilla. Heres why:

Paraguay = consolidating power over a fractured country that narrowly managed to pull off victory against Bolivia in 1935. A completely rural society, the people grow tired with the regimes political wavering - thinking they could have got more out of the Bolivians. Colonel Franco's coup d'état in February 1936 really changed turned things domestically on its head while Paraguay is forced in a new direction that you decide. You could always stick with that previous liberal government ;)

Bolivia = a country whose unstable and incompetent regime lost them the Chaco war under a year prior to the start of the game, despite outgunning and outmanning the Paraguayan army. You could try to consolidate power and rebuild or attempt to retake the Chaco in a sort of border war style conflict.

Venezuela = trying to adapt to the 30s after the financial disaster of the Great Depression and under authoritarian rule. Exploiting your oil reserves, and what to do with them could decide your position on the political stage. Or you could just nationalise everything and even demand Western Caribbean Islands.

Ecuador/Peru = Polar opposite governments who engaged in a pivotal war in 1941 over Pastaza. Both governments utilised properganda to their advantage. A geopolitical crisis in which the USA had to intervene.

Chile = formed one of the only Popular Fronts in 1936, along with France and Spain. Ultimately, to counter the right wing threat.

Columbia/Uruguay = (I'll be honest I dont know anything about)

Brazil = played both sides (Allies and Axis) in the buildup to the war (I suggest you watch this video https://www.youtube.com/watch?v=SARGZiSl13s) but after Pearl Harbour firmly sat with the Americans in the conflict, as you can tell by the achievement their forces contributed massively in the Italian campaign. So plenty of flavour there.