They're not as bad as people say. They came in my Cort A6 Artisan and were quite usable IMO.
I bought a set of Bart CBC not knowing what difference it was going to make but a lot of people recommended them as an upgrade so I figured why not. The CBC sound quite similar really except the highs are clearer and crisper - less harsh, and the lows are more defined.
I feel it was worth the upgrade for me, but if you like the sound (and I did otherwise I wouldn't have bought the bass) then that's cool, there is certainly nothing wrong with the MK-1 pick ups.