The type of set you describe is not, in my case, useless for wargamers. I often buy dioramic-style sets, for wargames.
They can be a source for unique figures: staff, engineers, command that often can't be found elsewhere.
Also, I like having little "mini-dioramas" on my wargames' table. For example, I have High Command stands (that have no strictly wargame purpose) of French, Russians, Austrians & Prussians (from various Strelets' Napoleonic command sets) that grace my re-fighting of Borodino, Austerlitz & Ligny.
Field hospitals & supply depots are equally useful "eye candy" in a wargame.
So the short answer is "Yes". A potentially good idea.