Is there (or has there been) any development or interest in more advanced circuit components?

[Sarke]

I'm thinking pre-made components like latches, registers, counters, adders, etc. I feel like the Factorio community would have at least explored this in the past but I don't see anything related to that in the mod list.

Has this been tried before? Is there interest in this?

[robot256]

The suggestions you gave are already present or trivial with vanilla combinators, if I understand you correctly. There are several mods that add new features, like the Filter Combinator, Stack Combinator, and several multipurpose programmable combinators like fCPU. There is even the Compact Circuits mod where you can open a single combinator entity and place many combinators inside it, like in Factorissimo.

I'm looking forward to the new combinator options in 2.0, but haven't needed any circuit mods myself in a long time.