the more general version of the elevator pitch is that being in an environment where all the code is written in one high-level language that is still fast is qualitatively different. you can combine things in all kinds of strange ways with surprisingly little work. I.e. the DiffEqFlux package takes about a hundred lines of code to glue together a GPU neural network library and some very advanced differential equation solvers.
realistically, it sounds like you are hitting all of R's strongest points currently, though. I suspect right now you would be pretty dissatisfied with Julia.
Here's context : https://jontysinai.github.io/jekyll/update/2019/01/18/unders...
There's nothing else like it.
Also here's the julia equiv to dplyr: https://github.com/queryverse/Query.jl