In Kibana 4.3 the fieldFormats array in the index.js of a plugin is actually never read out (i.e. the files never loaded). As a workaround if your plugin needs to register field formatters it can just add these files to the visTypes array, since the module itself anyway needs to register itself to the appropriate registry. So it doesn't matter which array visTypes or fieldFormats is used to load the file.
This behaviour is already fixed in the master branch, but unfortunately not in the 4.4 or 4.4.0 branch. It would be great if the appropriate fix could be backported to the 4.4 branch or if possible even to the next 4.3.x patch version (since it's just a bugfix).
I am not very sure, what commit exactly fixed this behaviour, but I am sure @spalger does know :-)
I guess it might have to do something with commit 6eeff7d where the fieldFormats is added to the use array?
Update corrected the commit hash to the more likely commit.
Btw, the required map in the UiExports.js was already there in Kibana 4.3.0 btw. So I think it really shouldn't be too much to do, to fix this in 4.3.
@spalger can you look at this?
Sorry this never happened @timroes, but I'm going to close this out since we're not doing any more 4.4/3 releases.