Anyway, you might like to see this ‘encyclopedia’ article, which has a short but interesting section on kimono and tea ceremony:
http://www.nationmaster.com/encyclopedia/Japanese-tea-ceremony#Tea_ceremony_and_kimono

In truth, I’m still trying to work out some of the rules of wearing kimono for tea. To my dismay, my sensei ruled out one tsukesage that I’d bought specifically to wear to tea. The reason: the colour was too dull and subdued, a slate blue-grey. She said I’d have to be in my sixties to wear it! So it’s squirrelled away for now. However, she’s encouraging me to wear colours that I think are a little too young for my age (44), saying that as a Westerner - because I look youthful, or due to my complexion, or something - I get a little more leeway. So I tease her that one of these days I’ll turn up in furisode :-)

You said, “Although the article only touches on kimono, the tea ceremony is of course one of the events to which kimono are worn, and much of the symbolism is shared.” This is very true. The colour and type of kimono (lined or unlined, with or without mon), and the design on the kimono and obi are all contingent upon the season, the particular occasion, and so forth. And in the case of the host, her kimono is chosen with the same care and consideration that she devotes to arranging the flowers in the alcove and choosing the tea utensils. It is all part of creating a harmonious whole that will create a peaceful impression in the mind of the guest.

It’s also worth noting that many of the movements performed in o-temae (the actual tea ceremony) assume that one is wearing kimono, and only make sense when viewed with that in mind. For example, there is actually a specific point early in the o-temae when, having knelt and placed the tea utensils in their proper places, you pause, straighten your kimono beneath you with a discreet tug, and “pause to gather concentration.”

The integral role of kimono in Chadou is one reason why my tea teacher is so very keen on having us all learn kitsuke, and why, in her quiet way, she is distressed when her Western students resist wearing kimono at all. No, it’s not essential to wear kimono … but it HELPS!