I don't know; for me, not being a thrash fan, the Black - Load - ReLoad - S&M run showed me that they were better than that. That they had a depth that a lot of other bands either didn't have or didn't bother to show. Personally, I love James when he sings, as opposed to that sound on MoP and RtL where he sounds like he's singing from the other end of a corrugated drainage pipe.
I'm not sure about the "I wish they combined them into one" theory; I would have sought out the other songs anyways, so it's kind of moot. I don't listen to all of both albums; I sort of prefer the more diverse songs (either Hero Of The Day or Bleeding Me is my favorite song from the two records) but I think they are what they are, a musical statement.