1. I admitted, some of it was my problem. I'm new to the game and I could have managed my economy better. Namely, I should have invested in more of the tax efficiency techs. It would have made a difference in what I could afford. My complaint is that this is something only a very experienced player would know, which means the game should do a much better job explaining how these factors interact and should perhaps be more forgiving to be rewarding to play.
Well, you seem to have learned the lesson pretty quickly desipte being new to the game, so it doesn't require that much experience at all - perhaps 1 or 2 games.
2. A lot of folks are missing the point. The question isn't whether armies should be expensive. There aren't only two settings, expensive and cheap. The alternative isn't making it so you can run a massive military for years of war with no impact on your economy. The question is, although they ought to be expensive, should they be THIS expensive.
I think there's a lot of people here arguing against a straw argument no one made.
Look, there's a reason army expenses go up when you declare war. A good rule of thumb for a good design would be a nation could afford to field a reasonable sized army at maximum national stockpile while at peace. When war is declared, this cost would jump two or three times and it would hurt -- probably a lot -- eventually causing debt unless you cheap out on maintenance or shift your economy.
The balance is currently way beyond that. A nation can now afford to field a reasonable sized military at something like 20% maintenance while at peace. War makes that cost absurd.
I can afford a reasonable sized army while at peace, at maximum stockpile; I never reduce it below 100%, as I want to feed my arms industry. If I want a world-class Navy (20 or more dreadnaughts), then I need to spend a fortune, but armies (as long as you don't spam guards, they're supposed to be elite and rare) aren't that overpriced.
You had half-guards. Each guard unit costs about 3 times as much as a regular infantry unit, so in your case that would have probably doubled the size of your army. A 150,000 man army sounds about right for Sweden's budget. Combine that with you missing the TE techs and inventions, AND switching to a government which can charge full taxes rather than half taxes, and suddenly we're looking at 75-100 infantry units on the same budget.
3. Arguments about what happened historically aren't helpful. The standard isn't the cost of once in a generation events like WWI and WWII. It's all the little wars you forgot about that happen every few years in the game. Even with WWI, this is a game and thus should be rewarding and fun. There are a lot of things in real life that I don't want to see accurately modeled in game because of lot of life can be random and unpredictable and not fun, and that's not how I want to spend my leisure time. No one goes to movies where a guy fills out papers for two hours, but that's a lot of real life.
It is rewarding and fun, once you've learned to play. You made a couple of basic errors and ended up trying to afford a decent navy AND an elite army, on 11.5% effective tax, followed by destroying your industrial base with high tariffs. That's called playing poorly rather than a broken game; it's like saying Chess is broken when you've played the whole game by trying to use your king offensively. You are standing in a position where you have the lowest possible government income and the most expensive possible forces, and then complaining that the military is too expensive for your budget.
Learn from the experience, have another go. If you want to afford a big military, then a government-on-a-shoestring L-F party with 17th century taxation law is not a good way to go.