That's too bad you can't get into Joy Division. Also, the Cure ripped off everything from JD. They should have stuck to their original sound circa Three Imaginary Boys. Disintergration's alright, but it gets a little tedious with all the slow tempos. Unknown Pleasures on the other hand has some variety. Maybe you should start listening to side two. That's got the faster songs (sans Disorder).
I think 'accessible' isn't the best term to describe the change in sound NO made. '80-'81 is a transition period. And there is plenty of stuff on PCL that's left-field. The band embraced a more melodic sound, definitely. And they got more into harmonizing various synth tracks with the bass. The most radical change early on was Bernard's guitar playing. His style really evolved, and he's not credited enough for that. (This is not to say I dislike his more raw, distorted, early style, but on the contrary, it was quite energizing in its own right.)