What I meant was, let's say average joe has a cordless kit with 2 slim back batteries. Gets the tool, uses his batteries, and thinks 'this is neat but kind of limited' which is exactly what you'd expect. Same exact thing with a cordless dremel.
The most obvious answer where corded is better is runtime. Some people use them for sanding so there's that. I have used mine for sanding in tight corners but it's not a regular thing. I will say though the finger sander that HF makes, if you don't mind regluing the velcro on it from time to time (same as I've had to do with every brand of sander backer) is pretty sweet considering.
Cutting grout is the easiest example I can think of. Granted this was back when I had only 8 M12 batteries but I had to do 'a whole kitchen floor' in the sense I need to make precise cuts for removing a few broken tiles, then replacing them. I guess I could have made many trips to and from the charger but it was easier to get the corded one out.
Generally these tools you don't really rely on power so much as the motion of the blade. But faster movement eats up batteries a lot. Some things I do like breaking down scrap etc I can do at lower speeds; doesn't take much real work to go through cardboard and many plastics.
So generally I use mine for flush cutting wood, cutting various plastics, and (dont laugh) as a kind of scribe with ply & boards most of the time. Sometimes mine have been used as a scraper, with the grout blade, sander, as a carpet cutter, although none of these regularly. I would say unless I need to be portable, or it's overhead such as moulding work, I do not use the cordless one 9 of 10 times. In fact, the last time I did use the cordless was just so I don't have to swap the blades back and forth.