We investigated this when we redesigned the taxon page in 2016 (yikes, that was a while ago). I just made it so you can see what we did by appending test=interactions to any taxon page URL, and I’ll use examples to explain why we didn’t develop this any further.
The big problem looming over this whole feature is that observation fields are a bad way to model interactions. Since they represent a totally uncontrolled vocabulary, they’re rife with synonymous fields, so it’s hard interpret situations where, for example, there are both eats and preys on interactions, e.g. https://www.inaturalist.org/taxa/117520-Enhydra-lutris-nereis?test=interactions. What’s the difference? Why are both supported?
Another problem is that using observation fields to model interactions means that one of the two taxa in the interaction is not subject to crowdsourced identification, so anyone can say that oaks eat humans and there’s nothing the community can do to correct that. As an example, here’s a butterfly that supposedly eats itself: https://www.inaturalist.org/taxa/51097-Papilio-zelicaon?test=interactions. It doesn’t, this is just due to an erroneously added observation field. Site curators could just delete this field, but that’s generally not how we like to perform quality control at iNat.
On top of that, we really wanted to incorporate data from GLoBI, since we like them and we think it’s cool that they incorporate iNat interaction data, but mapping taxonomies and field semantics proved a hassle, and again it presents the problem of data that the iNat community can’t correct if they find errors.
What we’d like to do is to make a new feature for interactions where an interaction is a relationship between two observations with clear and controlled semantics (to the extent that that’s possible). So instead adding an obs field that says an obs of an oak represents that oak eating a human, you would create an interaction and have to choose two observations, one of an oak and another of a human, and choose “eating” from a menu of interaction types where “eating” means “taxon A is putting all or part of taxon B inside its body for the purpose of personal metabolism” or something. Other users could then vote on whether that was the correct interaction type, and the two observations could be independently identified. We could try and pre-populate this new kind of data with observation fields, or at least make a tool that helps people review their own interaction obs fields to make new-style interactions out of them. That’s a lot more work, though, and it hasn’t really been a priority, so we haven’t gotten around to it.
Anyway, that’s a long way of saying that I agree this would be cool, but doing it right will take considerable effort.