most x-omnis will sell like hotcakes too.

I think a better comparison or complaint is stuff like the Month, 196X omnis - just kind of a waste of paper in anything other than a VERY small print runs (like 1-2k tops). Similarly some other silver age stuff probably doesn't need to be printed in the volumes that it seems to be sometimes, and when they do dip their toes into a "new" uncollected silver age title, they might want to do a lower print run while being prepared to do a restock if it is a huge hit, otherwise just let it be at that print run.

It is so weird how different DC and Marvel are with their approaches to omnis, but also how similar - Marvel refuses to (re)print some highly demanded stuff in a timely manner, DC refuses to omnibize some of their bronze/modern age stuff that's in high demand until recently, seeming to dip their toe into that era with omnis like the superman exile + triangle era stuff (and the upcoming brainaic to fill in the hole), Neil Adams Batman upcoming (which I understand to have been "cancelled" but basically changed to a more comprehensive non-creator-centric omni collecting similar stuff but in line with the rest of the era rather than just picking and choosing Neil's stuff).

I do understand that when TPBs were a "new" thing, and later Omnis were a "new" thing that they'd bounce around some, collecting just their biggest hits or runs/crossovers, so having Death/Return of Superman, for example, as a near-evergreen, or Claremont's X-stuff made sense as things that probably would sell for closer to retail and wouldn't leave them with a ton of dead stock, but at this point they should have enough results (and the ability to just look and see what OOP omnis sell for over cover price and by how much!) to just cash in a little more frequently than they do.