Not as many as you would want. True there are many (a lot really) rock styles represented and you can find just about any generic rock style. You will however be hard pressed to find more than handful of styles that you can specifically say that sounds like so and so. The Dire Straits one is pretty spot on though.

Hard rock is severely under represented and you will find a hand full of recorded generic hard rock styles. The LA guitars or a few of the praise and worship guitars for example.

You have to work really hard through using the DI guitar realtracks and edit them in a DAW to start creating specific rock band styles. If you have an amp simulator you can dial in just about any iconic band sound you want. So in a round about way they are in there you just have to work to get them out.

I for one would like to see more hard rock rhythm styles but that's just me. I also wouldn't mind a few more hard rock soloist realtracks by an actual hard rock soloist. I love Brett Mason but the metal soloist are severely lacking in iconic but generic metal guitar riffs.