Well, I never even tried to do WC in previous EU installments. I am more keen to create world superpowers, rather than `to snatch up as much land as possible`. And it's not even realistic, so to speak.
And I made Brandenburg/Ottomans/Byzantine/Russia/Mali superpowers all in 1600s. I was happy with result, I never really noticed all that horrendous bugs you describe here. All these games was reliant on land, not naval, and my trade superiority only fired so much late into game, strictly due to me controlling hefty landmass, rather than any kind of naval/trade focus.
And idk about any serious army flaws, I had some problems with Russia, I had severe problems with Byzantium; I went 2 land ideas straight away and lost 4 to 11 land tech to my neighbours, but it's was quickly solved with mass hiring merc regiments of proper land tech level and raping everybodies asses around. With brandenburg (read prussian ideas, it's insane!!) I demolished multiple armies thorough, including several 30k vs 80-90k wipes in my favor.
Game works. Amount of new options, compared to EU3 is staggering. Despite of my hate to all heavy graphics and laggy overall game, it's just outright plain better than EU3. Worthy purchase, hands down. I can't even imagine how great it will be after all patches and mods.
Seriously, stupid sliders compared to new 3 types monarch points separated from treasury? No contest.
p.s. I still cry how bad TW: Rome 2 now