What They Found in the Attic of Westminster Abbey

They don't. At one time people believed that architecture itself could direct people's attention towards God by creating an uplifting and sacred atmosphere condusive towards worship. People also once believed that music, like architecture, could be sacred (just as a common building could be viewed as inapropriate to for worship, so also could common music be inappropriate). Largely as a reaction to RCC idolatry, some rejected such ornate features. But more than that, some rejected the idea that architecture could be a form of, or contribute to, worship. The same is true of hymns, which were rejected in favor if actual psalms. Some maintained everything should be plain so as not to detract from worship. So the shift was in viewing these things as somehow facilitating worship to viewing them as obstacles.

Today we seem much more utilitarian when it comes to these things. One notable and interesting exception is those who reject sacred space yet cling to sacred music (some reject things like stained glass while insisting on traditional music styles).

But no one worships stained glass.