Well, I know it's popular speculation, and I even started a thread about it, but it's yet another reason why I get the idea that JM doesn't seem to like the other guys very much. He's rarely hanging out with them in videos, plus MP's comment about him never being in the same room, then it seems as if he's all but removed himself from the writing process on the last two albums. In the Spirit Carries On documentary he comments that this album reminds him of old times jamming with JP - my question is, "why did it ever stop being like that to begin with?" It is obviously an integral part of what made DT work in the beginning. It just seems to me that JM has either been voluntarily diminishing his role in the band over the year, or unconsciously pushed out of it by the stronger personalities. From what I've seen of him, he seems to be a rather passive personality, so I suspect the latter is the case. If any of this is true, it's no mystery why his input and enthusiasm have been diminished on the last two albums. I've felt like he was phoning it in with his playing, and that's why the bass has been buried in the mix - there's not much to hear. Hopefully that's changed now. Conversely, I'd be willing to bet that he blows the doors off on the new Jelly Jam release, which was recorded during the BCSL time period. It all has to do with the creative environment and how invested the individual is, and I just don't get the sense that JM has been very passionate about some of the newer DT material.
My two cents.