Coming from 10+ years in Zotero and then Mendeley where I've always used the web scrappers of the applications, JabRef's Select Entry Type forms seems overwhelming at first sight with all the different article types. A new user wants to create his new entry as simple as possible, and looking at that form gives them the feeling that they have to study these article types first. If a user has trouble to carry out the most basic operation in a program, they will probably abandon it, even if the program has all the features the user needs.

Since in the vast majority of the cases all the data related to an article is already on the web Web search or DOI is used, and probably should be used to avoid typos.

My proposal: by default hide the different entry types and leave only the ID type and ID fields. The rest can be blended out with a radio box, or these could be put into another tab, or put below the ID field and be separated in a visually strong way. This would make it clear that entry through the ID is the best, and advised method for creating entry for an already existing publication.