BD is devided into 4 acts, which relatively control the level of monsters.
If you are more advanced in rpg gaming techniques (other than changing your difficulty level), You can start avoiding the Battle Fields. I am playing on hardore mode, and only use the battle fields as a trading post.
Also the fact that you stop getting XP once you are 8 levels higher than the monsters, serves as a self limiting device for your char's level in regards to the area that you are in. So you are kept in relative level of your oponents in anycase.
What i did not like about Diablo2's idea of the monsters are the same as you, is that i dont think that a level 49 skeleton is very realistic... And also the game layout is so much different... Diablo2 you spend the majority of your time in dungeons, where every level gets more difficult... this is realistic.
But since BD and DD (By the way you NEED to get this... if you like Bd, you will LOVE DD) are mainly played above ground, it makes more sence to make some areas more difficult than others (which also keeps most players to the general story line, by making them go from A to B instead of from A to P and back to B).
