Great news, this feature is now live and ready for use. Thanks Gijs for putting this suggestion forward and everyone else who voted for it and moved it up the priority list.
I hope this helps you manage your products and report on sales better than ever before 
And, as always, please do let us know any feedback as it’s hugely valuable to us!
As a bonus, this feature also allows you to (optionally) enable a tag as a Trade Store category, as requested here.