Some of stuff here is wrong.
Not every region has a resource. Some do and will either boost production of a certain resource (plastic, fuel cells), or allow a special building to be placed. For example, rare materials allows you to build a solari-producing building, which is otherwise impossible to raise, and naturally spice allows for fefinery. Every village has its own bonus (sometimes it's passive income like +3 solari, sometimes it's bonus XP to units fighting in the village's region, sometimes it's bonus to output of a certain resource). On top of that, there are also special regions that give bonus to Hegemony and another bonus (resource output, special building construction like the iceberg).
You're saying there's a limited selection of buildings, but there's like 18 of them. You can also build special buildings in your main base after reaching 2k Hegemony, and completing districts in a certain way nets you various bonuses.
Milita slots vary by faction, technology, advisors, etc. Harkonnens can get up to 6 slots iirc.
As for tech, the bonuses look small, but they're huge actually. Stuff like Hegemony for every village producing water is insane if you're economy focused and can afford placing windmills everywhere. Plus tech unlocks the special buildings for your base which can give huge boosts to your win condition as well.
