We could have something like
nixpkgs/nixos/modules/stacks/datascience
and then
stacks.datascience.enable = true;
To address the the problem of ‘opinionation’ of Nixpkgs we would then have some sane defaults which correspond to the orthodox conception of such a stack with extra options to allow tweaking. Worst case a stack could be forked.
I think putting this in Nixpkgs could be very nice for new comers: they could follow a simple tutorial and very quickly have a full stack up and running. Eventually if and when some Nix language changes would take place, we could even consider distinguishing service modules from stack modules explicitly.