For my current run, I would like to keep on the older approach instead of the revamp you introduced from 2.x onward, could you please produce a 1.8.1 version for 2.1?

Seconding this, but 1.8.2 with the 1.9.1 fixes (unless it was introduced with 1.9.0) would be better imo

Will not happen

for the record, doing this on an already existing mod, breaking saves so thoroughly warrants its own version, is really unprofessional, going from expanding production options to a slight overhaul is counter-productive.

I believe we can fork your mod from 1.8.2 with 1.9.1 fixes as UPD-8 comments?

The license should allow that, and id be fine with someone forking it

what would an appropriate name be for the mod? when I release it can you put a disclaimer on your mod page linking to that one for those that want to keep as it was?

Spitballing here, but would pulling a Runescape Classic and calling the fork 'Age of Production Classic' work?
Simple, but it works in my opinion.

AoP Classic, AoP Legacy... stuff like that

Great suggestion, thanks