Using wares for new purposes happens all the time, and I am quite guilty of doing that fairly often. Most of the time, it involves using some teaware for slightly different purposes than they were originally intended. Other times, I am using things entirely out of context to suit my needs. Some are mere modifications, others are complete changeovers.
For example, when there’s a lid-less yixing being used for a fairness cup, I’d say that’s at least somewhat misappropriating the pot. Lots of people do that, for reasons that may be quite varied, from a yixing that has a missing lid in need of some use, to wanting to season a pot for no particular reason.
In my case, the most often misappropriated ware is my pewter bowl, originally intended for fruits and other goodies, and now I use for holding my pot.

Over time, I noticed that it’s doing some damage to the mother-of-pearl decoration to the bowl, so I’ve stopped, and instead am using a dish for that purpose.
The wooden tray you see in the picture here is for the Japanese sencha ceremony, which basically means it holds the cups with saucers. For me, the tray is where the action takes place, and does the job of framing the area over which I make tea. I used to use a water-holding tray with slots, the kind you find from all sorts of teashops in China and Taiwan and Hong Kong, but I no longer like those. In fact, I no longer own one of those as I’ve gifted or discarded them all (except a traveling one, but that’s kept only for mobility purposes).
Many cups I use these days are also not intended for tea to begin with. The smaller cups are generally sake cups, such as these:

The gaiwan is a gaiwan, but the cup is a sake cup. Many are nicely decorated, with a good size for gongfu tea purposes. Some might not like the straight edges, but I don’t mind them. They work.
And then you get into territory that’s a little more muddy. Take, for example, the gaiwan.

This is not a gaiwan meant for brewing. This is a sipping gaiwan, where your tea is supposed to sit and you sip from it, gently pushing the leaves aside with your lid and holding it by the saucer. Instead, I used it to make some green, with a much higher leaf to volume ratio. These days, we’re so used to using gaiwan for that latter purpose that the original is almost completely lost, except in period dramas. That cup, though, is a teacup of sorts, although it can just as well be used for wine (Chinese, that is — this is not a sake cup).
But then, what is a teapot, a gaiwan, or a teacup anyway? It’s just whatever you make tea in. It doesn’t really matter if it’s a brown betty or a silver Korean teapot. It only matters what you do with it, and sometimes, items find a second life, much like buildings (or in some cases, people) do.
I just want to say that I still find your blog and writing extremely relevant. Thanks!