The simplification of this game rule has as negative consequence that the terrain map mode looks less naturally now.
Wait, what is terrain map mode? Is this something different from political map mode which I see on 99,9% of all screenshoots posted on this forum?
Further, refinement instead of simplifiation, should be the rule when changing a game rule. A better solution would be i.m.o. to restore the landscape variation in a province.. and to prevent unpredictability in what landscape type a battle takes place, let the game engine determine the landscape by looking from what direction (specific neighbouring province) the first attacking force comes.
This is one of these game design ideas who sound awesome from utopian point of view ('I'd love to play strategy game when you can command 100 000 soldiers in one moment and turn into one and play shooter in another!') a and would be the most horribly ridiculously impossible stuff to put in a computer game.
The first problem would be taking 2000 provinces and for each single one of them establishing a 'connection' with neighboring province and decide which terrain it gets when attack is conducted
and vice versa, then include naval invasions, rivers and maneuver, good luck you spent weeks on doing this ridiculously convoluted programming task you could spent on designing Greatly Enhanced Governments DLC, next weeks on balancing it and then you would face inevitable crash because...
Both issues are solved then, and.. a new tactical feature, on what location inside a province and to what direction is in a give situation the defence organized, is introduced too. This can also introduce issues as flanking attacks from other directions, and how much this has negative results for the defending force based on tactical and manoeuvre insight of the eventual defending commander.
Read this slowly again. Now imagine yourself, sitting in front of computer, in front of a map of 2000 provinces, each of these provinces having few terrains, each of these provinces neighboring few other provinces, each of these provinces having few possible defensive positions.
Let's assume there are 2000 provinces, on average 4 various terrain types in each province, on average 4 neighboring provinces, 7 levels of maneuver of one general and 7 of another (0-6), on average 4 defensive positions possible to take. Now I'll do some awkward math but that isn't important, general rules and scale is important. Essentially each province has on average 4x4x4 terrain scenarios possible to emerge in battle, 2 possible scenarios of maneuver comparision (offense-bigger maneuver or defense bigger). So here we go, in this theoretical scenario there are 128 possible scenarios including all simplified variables; for each average province. I didn't include flanking and other cute variables you could include, I don't even know what the hell is happening to rivers. So there are 2000 provinces and for each province there are 128 possible results of variable calculations, so there are 256 000 results of battle terrain calculations, and somehow each of them should be calculated in the background, presented on UI and processed by player's brain.
So essentially you sitting in front of all those possible outcomes, in real time, being engaged in a great coalition war where 600 000 soldiers of 23 armies of 14 nations and 11 generals coming from different directions with variosu maneuver values are engaged in sieges and battles in Balkans, among rivers, straits, woods, hills, mountains, marshes, grasslands and maneuver modifiers, coming from multiple provinces at once, from many distances at once, among sieges sorties attrition shattered retreat artillery and cavalry. You are fighting 4 battles on three fronts: one naval landing, one major battle, one counter siege and one minor sortie. Now imagine yourself sitting in front of that clusterfuck and sitting with a pen and paper and calculator, switching from political mode to terrain mode every 5 seconds, to try to predict what the hell will be the terrain the battle will be happening on, with UI overcrowded with tooltips showing potential terrains, neighboring provinces, flanking, defensive directions, only to lose because, surprise, 74th reinforcment force of 11th enemy from X province from Y direction of Z terrain with L maneuver change calculation R and gave you negative modifier F to terrain which made you lose a battle, a war, a country, an ironman save and a sanity.
I don't know who you are, I don't know how high IQ and computing abilities your brain has, but I bet nobody ever would be able to turn such insanely convoluted design into something being enjoyable in a computer game.
Hell, I am pretty sure a few tweaks here and here, two more variables and predicting outcomes of similar system would be impossible with computing power of modern computers (non - quantum).
Think about a situation as 200 years ago, Napoleon was on its way from France to Brussels, resulting the Waterloo campaign. The Anglo-Dutch defence was organized facing to the south in a landscape south of Brussels and the Prussian army came from the east (in the game from the Liege province) to the right flank of the French army. If Napoleon came from lets say the north (the direction of Antwerp) the defence would be organized facing north at another spot in another local landscape situation, but still in the same game province.
Think about a situation on real historical battlefield: soldier can suffer from chronic diarrhorea. We will reflect this in our game, this will be fun because realism is awesome. The player will have to predict the strategical countermeasures against this challenge, including proper medicine, healthy food and filtered water. If diarrhorea happens he has to invent a way to fight while having it, like English archers on Agincourt [historical fact]. It will be hard to have a decent, average accuracy of 3% [historical accuracy of casualty inflicting archer arrows vs all arrows shot on Azincourt, basing on estimates] with digestive challenge and our physic system of dust particles messing with sight range.