This was a historic design decision that now seems sensible to reverse. Let us therefore display these exactly as they come from Wikidata everywhere - SE previews, search results, articles, etc.
When you write description of article with first small letter, it looks like this:
In preview is letter transformed to capital:
But result is okay, with first letter small:
& diff on Wikidata
App version is: 2.7.50307-r-2019-12-16