Hi there!
An earlier version of AR (sort of) did this (called "Fewest ingredients first"), but it didn't play well with other mods (such as Bob's Modules, which added recipes with new ingredients). With Factorio 0.15 it became obvious that the old "Fewest ingredients first" wouldn't work well any more, so I replaced it with an ingredient filter: In the GUI (Shift-T) you can toggle allowed research ingredients. So if you only want AR to research techs that require nothing else than red/green science, then you toggle all the other ingredients off. By default all ingredients are allowed.