I always wondered myself what would had happened if MK would had been more open to others contributions, in the sense of allow one song ot two by David or John even for b-sides of singles. Their songs are good, not excellent as Mark's, but good in their own way, and I'm sure that arranged by the whole band, with MK guitar, it would had worked.
Take "Bernadette" for example, a song by David, which is not excellent but it's good on its own way, with the rythmic by John and Pick, and with MK guitar solo and lead guitar, the song sounds quite well, and as a b-side for any song it would had worked, even it would had fit in any DS record. It would had been less good than the rest, but every album has some excellent songs, and some others that are less good, but good on their way.
Also thinks that "Sacred loving" was on the demo of the band. Think in a band that has very little money, and they expend the one they have (from a money that John inherid) recording five songs, between them, one by David. If it wasn't good enough, why spend time and money recording a song by him, instead of doing just four MK songs? That sonng was different from the others but had an excellent work by John and Pick, and also an excellent guitar work by MK, so it would had fitm as minimum, in a b-side.
I'm one of David's patrons on patreon, and in one of his podcasts he said that first thing he did when left NY (and the band) and arrived to London was buy a house for himself, and buy a piano, and started playing things, and one of the first things he came with was the piano melodies that starts his song "Soul Kissing". In that podcast he played on the piano that melodies and first thing I thought was "that would had fit very well in a DS records with the help of MK guitar arrangements". His piano skills are far from the ones by Alan Clark, for example, but would had added something extra to the band.
Funnily, John Illsley played bass on that song, and he's on the videoclip as well, a quite bizarre videoclip in my opinion
https://youtu.be/4BwSPd5BFu0?t=157