On release, I'd agree that a lot of the Shgoun 2 maps were repetitive and boring, but if you load up Shogun 2 today after they added an assload of maps, it's honestly very entertaining. Massive mountains, deep valleys, ACTUALLY different castles. Then there are the maps which are 60% bamboo forest, maps where it's predominantly regular forest, coastal maps, etc. etc. etc.
And then there are the maps used in the campaign missions which are just barrels of fun. So much so that I wish they would use some of those maps in the actual grand campaign.
Still, I'm glad to see major populated cities making a return. Though I'll wait to see if they'll actually have proper ones outside of scripted missions.
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As for modding support, I'd cut them some slack. Honestly I believe them when they say the game is a lot more complicated than the previous ones with far more interrelated LICENSED software being used to produce content. After all, they can't just willy nilly allow people to use proprietary third person software that they licensed for free. So there's a lot more going on there.
You can't really compare this to older games like Medieval 2, which while amazing... is honestly a lot more simpler in every single way. The animations in Medieval 2 for example is almost nonexistant whereas the animations in Shogun 2 are crazy detailed. The modelling, voice acting, scripting, it's all just a whole lot more work. Even if they made the modding tools available, I highly doubt many people have the time or the energy to put in the same amount of work as CA's dedicated staff to produce something like Stainless Steel for Shogun 2. Even Stainless Steel took many many years to put out.
As quality of games increase, I think this is something we just have to get used to.