There is exactly one Balrog in the game, all those other cool things you mentioned do exist, but they are very uncommon. Uncommon as in there is only maybe 4 types of Goblin in the game (4 "clans" or whatever, each clan has maybe 4-8 different types of goblins, such as warriors and... warriors, that all look and act very similar but have different names such as Goblin Scout and Goblin Crusher). As for the other types of enemies you listed... I saw none of them, except for one troll in a cave that had been turned into stone.
The enemy diversity (and general diversity of the game) sucks, really badly.

Like I said, the developers had such a wonderful world and setting to base the game on... But they totally fucked all that up and 99% of the time you will be killing pigs or wolfs to collect 8 pig testicles or 5 wolf paws for some stupid quest (and to make it worse you WILL be playing as a Warrior, because all the classes are basically that, except for Loremasters, which are suppose to be Mage like but only have a single skill that is even worth using and even then it is much easier to simply use a melee weapon anyway, effectively making you a squishy warrior with useless magic).

It's probably your vid card then. GW requires just barely a slightly better vid card than WoW, but requires a lot less RAM etc.

WoW requires a geforce 2 or higher while GW requires a geforce 3 or higher. Considering that video cards are not only more expensive than ram, but that they also have more of an impact on performance than just more ram, I would consider GW to have higher requirements, if only by a bit.