Every time I look at BMP, I am like “the list is insane”. So here is an idea how to fix some issues, with BMP and a few other things.
Lets create a low-tier counterpart to AML (lets call it BML for now, Basic Materials Lab). It could process the lower tier elements, namely MG, S, I and CA. Maybe even CL+NA. Taking a few recipes from SME (S) and CHP (CA, CL+NA) would only do them good.
Such BML could be a t1 building imho, only CL+NA feels like a bit higher tier recipe.
BML might be an awkward starting building, but I would compare it to WEL, they feel quite similar in utilization pattern - niche and overproducing early, but vital later.
PWO might be better suited for CLF. CLF is one of the terribly early overproducing buildings that you only build as a sacrifice and necessary evil when your corp starts technicians. Having PWO would magically make it viable for solo players and it would make a lot of sense thematically too. It would certainly increase price of PWO, but their break-even cost is about 400 each for non-extraction buildings. I have only run napkin maths, but it should be possible to make them cheaper than that even in CLF without any additional changes to the recipe/building. (Could someone better at maths verify?)
SUN is another recipe that could be moved to CLF. Looking at the universe, we can easily start building CLFs already, but I dont think any POPI is popping up quite yet so gating Safety-supporting material behind settlers does not sound too rough. Given current balance, POPI does not seem to be important for Pioneers in general. And uniforms are clothes so they would make sense in CLF.
My last target (for now) is REP. I would move them to FS for the exact same reason I described for CLF - sacrifice, necessary evil, thematics… You get the idea I am sure.
Even after such changes, BMP is still a really versatile building with maybe still too many vital recipes (OVE, MCG and PE will always be needed a lot) so it would not kill the building and the manufacturer start at all.