ran into this myself just today, but with Symbolics.jl instead of SymPy. I just needed an algebra scratchpad, and Symbolics was.. barren. and uninviting. I thought of reaching for Mathematica but resorted to pencil and paper, like a barbarian.
same deal with solvers more generally. the coin-or stuff (e.g. Cbc) is slow and buggy, Cplex and Gurobi are far better but very expensive. where are the PhDs in this field? what are they building?