Would it be possible to add in version of the Java Snippet and Math Formula nodes with an optional interface like in the Missing Value node for creating multiple new variables inside that node? This would greatly simplify workflow when creating many dervived variables.
just as a thought: Maybe those identical computations can be accomplished with a dedicated looper (meta-) node in 2.0 (or the version thereafter). I'm thinking of a looper that enumerates the different column names and uses a scope variable (something that has been discussed in a different thread) to address the current column of interest. Nodes in the loop body would then operate on a single column (different in each iteration). Perhaps that is also a possible solution to your post concerning Missing Value dummy variable node?
But then again you have problems like merging results, complexity issue (multiple data iterations) and so on. Let see.
And to answer your question: Yes, it is certainly possible to add appropriate functionality to the java snippet and math formula node (basically all nodes, which work on a single column) to make them work on a set of columns.
But then we have limited resources and a slightly different focus (new features). I'll add your request to an internal feature request list - but that is not going to happen anytime soon.