The following needs to be done:
rename Simple JSON to Legacy JSON
add info button explaining what Legacy JSON represents
Legacy JSON should be visible to the Advanced users only
Notes:
1) I think we should keep the name "Simple JSON" so that people can make a connection with "Simple JSON" in older versions (but add the text "deprecated" and an info button)
1) For import nothing will be done, I hope auto format detection will be implemented soon and solve most of import UI complications