Hi there Iv got the game too. There are many patches for the game but these just do things like balancing gameplay and fixing bugs. The pop limit of 200 is the restriction and no one modifies the game nowadays coz its quite old.
You should be happy with 200. The original Age of Empires had a limit of only 50, now that IS RESTRICTIVE and no one tried to push the limit on that so yeah AOE 2 is the same.
If you want less limits then go for Age of Empires 3
Sorry