Such a perennial problem for me! For reasons parallel to yours.
I often intuitively start with singular: This tiddler about Du Bois should be tagged as philosopher
(or whatever).
Then at some point, I develop the tag tiddler itself to offer some kind of overview. At that point I regret letting the tag be singular, because the overview tiddler, with its list of many things so tagged, looks very funny with a singular title. And any solution that involves captions or aliases threatens to compound the work I face down the road.
I also think that the plural tag more clearly directs web-visitors to realize that clicking on it might give them a window into other tiddlers under that category. For that reason, I’ve tried to get into the habit of starting with plurals from the get-go.
However, I’ve also gotten into the habit of linking directly to relevant tags in wikitext (that is, making an inline link of the <<tag philosophers>>
kind so that the dropdown is right there, with link to the actual tiddler available at the top: We'll consider various <<tag philosophers>> from this tradition
). But we don’t have an easy syntax (so far as I know) for doing with tags what we can do with pretty links to tiddlers: "Not everyone counts Du Bois as a [[philosopher|philosophers]]"