I'm not sure why Owens & AJ don't mesh in WWE. It's weird. On paper, they should put on MOTYC every time they wrestle.
I think part of it is just that WWE spammed the match too much. Way too many rematches can just make audiences sick of seeing it.
It didn't help that their last PPV encounter had an F'd up finish, and that was coming after a CO ending in the first PPV encounter (which I didn't have a problem with but following it up with a match with a messed up finish kind of set a bad trend).
As has been stated, it's very strange how two mega stars like The Undertaker and The Rock never had a decent match between them. They just had absolutely zero chemistry.
I think part of it has to do with when they worked with each other.
If I recall correctly, their first PPV match was at Survivor Series 1998 in the Deadly Games tournament. That match was pretty much just designed to get Rock to the finals, and nothing else. They made it quick, to the point, and moved Rock forward.
And then they had a title match at King of the Ring 1999, during a time when Undertaker was beat to shit. This was a few months before Taker took extended time off to heal up. Prior to that, Taker was in pretty bad shape and not entirely capable in there. Keep in mind that Taker was coming off of a horrible Mania match with Bossman, a lackluster match with Shamrock, and generally less than stellar work.
And then they had a match at No Way Out 2002 which was overshadowed by constant interference from Flair and McMahon. Basically, they just wanted to get to Flair/Taker at Mania, and this was just a springboard to get there. It could have been anybody else up against Taker and it would have virtually been the same.
Now you put them together in 2003? Might be a different story. Put them in a PPV main event in 2001? Might work better.