Research progression

Something I noticed today, I can select research which requires yellow science packs, but I can’t research yellow science yet. Is this deliberate?

Absolutely. Just like Motors for Larger Miners, Carbon Nanotubes are a prerequisite for Yellow Science.

Developer has actually made the research tree easier, because there minimum city level requirement anymore.

This has nothing to do with city level requirements.
I think it makes no sense to unlock research requiring yellow science, like for instance Uranium Mining, if Yellow Science itself can’t even be researched yet.