Hi!
away from the old layout and that is very welcome. Singling out the external resources does not make sense at this time.
It is true that more structure in general would be good, but I think there's some difference between external IDs and other properties - namely, the former convey almost no information useful to a human in most cases (though definitely not in all - in some cases, that's exactly what one may look for). So internally (on the data level, etc. with respect to qualifiers and all other data model things) they may be the same, but if in the UI they were separated somehow I think that would help making both cases more efficient and make finding way in the data easier.
When you want your information is a more readable way use Reasonator.
Reasonator is excellent but AFAIK it's read-only and one can be lost in the wall of IDs even when editing. I think having them in separate section (and, further, having properties grouped somehow in general) would be helpful.
Having the external resources in there has already proven itself as being extremely important.. OCLC will use Wikidata as its primary source for linking its sum of all knowledged to our sum of encyclopaedic knowledge.
It's indeed important, so I think the idea is not to diminish their importance somehow but to give them separate space which may lead to improved workflows for both "data" properties and "external ID" properties.