☐ cool new feature
☑ could help many users!
☑ removes something that feels like a „bug“
☐ nice to have
☐ nobody needs it
What inspired this wish list request?
Insert Into automatically "flattens" the expression if the Head of the first and second argument are the same - causing some JMP Expr() weirdness .
For lists the automatic flattening might be OK ... let's say for 60% of the use cases - but it "hurts" for the remaining ones.
And for all the other (non-list) cases it's actually NOT what the user wants.
What is the improvement you would like to see?
Please add an option flatten(0|1) to Insert Into.
Why is this idea important?
less JSL weirdness → happy users : )
other wishes from 
I just found:
How to insert a list into another list
with the nice workaround:
insert into( result, evallist( { p } ) ) A very nice combination of tricks to fight against a helper function of JMP which automatically flattens an expression while inserting.
Every user who understands and remembers this trick for his daily work can be proud.
It separates him clearly from all the other users who just want to use JMP to solve their problems ; )