The notion that we have so many editors who are engaged in adding sources is based on what? IMHO it is wishful thinking that sources matters that much to most editors. When you say that they cannot manage statements as well as sources you miss several important points.

• It is more fun to add statements than sources, statements are useful in other languages.
• statements are used in info boxes so they are part of the article that is written
• statements help build a concept cloud around a subject
• sources as part of a "library base" or as part of Wikidata make sense because this does add value [1]
  
• sources on their own are only supportive to an article, they are a dead end

Manually importing of statements is done extensively, I blogged this week about Mrs Nataliya Kobrynska [2] and as a consequence I imported over 1000 statements.Manual import is an existing practice and consequently it is not part of the paper. It is however possible to do away with much of the importing when the content of lists and categories are based on statements .. Much of the basics for such a thing is in place. It will likely change the practices in all Wikipedias when we go that route.

If there is one problem with this vision, it is that it is too Wikipedia centric. The problem is not Wikipedia an sich but the problem is that there is not one Wikipedia but there are so many of them and they all have the notion that they know best. At that they are wrong on principle. A good example are subjects that are "local", this is where the local language typically has an advantage over languages like German, French or English. I am currently adding info on legislative representatives from Kerala and they are much better described in Malayalam [3]. I am however adding info from English..

In conclusion, I understand your point. However, when you look at it from another point of view it is not what will move us on to higher quality for our projects.

Thanks

      GerardM

[1] http://ultimategerardm.blogspot.nl/2016/05/wikipedia-citations-librarybase.html

[2] http://ultimategerardm.blogspot.nl/2016/05/facebook-nataliya-kobrynska.html

[3] http://ultimategerardm.blogspot.nl/2016/05/wikidata-kerala-mla-constituencies.html