I've been wondering lately, hope you can help me.
Should we understand
"You think this is easy, realism"
meaning that reflecting reality accurately is a feat, or
"You think this is easy realism"
implying that it is a cheap, inferior form of art which should be avoided?

The version of the lyrics posted on TW is the first one, with the comma suggesting that "realism" explains "this" and apparently authorized by the pause after "easy."
However, the pause may be purely musical, not linguistic, making "easy realism" a noun phrase, and this is indeed how the lyrics are printed in the CD booklet.

Although I always took the first interpretation for granted, in fact never suspecting the second one existed at all precisely because DB pauses between "easy" and "realism", the latter now seems obvious, following the lines "I'm home, lost my job/And incurably ill", as a comment on their reek of tear-jerking socially realistic sob story int the neo-Dickensian vein.
I also suspect that DB deliberately paused between the two words precisely in order to prevent a definitely unambiguous interpretation and surround the DJ's (if not his own) appreciation of realism with ambiguity.

Wear your wound with honour.