I think I can see a future member of aforementioned group
If you do not like the dress code, apply elsewhere. Hundreds of years of tradition should not be dispensed with because of a few extreme left wing malcontents not liking it. Oxford has a number of wonderful traditions, sub fusc being one of them.
Having actually sat exams at Oxford, I would say wearing sub fusc was actually quite calming for me. I never heard anyone complain once about having to wear sub fusc before any of the sets of exams I ever sat; if anything people tended to like the fact that everyone went in looking the same and you didn't need to worry about what to wear. Others have said (be it to me or in articles defending sub fusc) that it gives them a sense of confidence, whilst some simply like the fact they are taking part in an ancient tradition which every member of the university is a part of regardless of background or College.
If wearing a gown or bow tie/ribbon stresses you out so much, I would contend you have some quite serious issues and that Oxford as a place may be unsuitable for you and your well being.
You are displaying your ignorance of the issue. Sub fusc is already compulsory. The fear is that if it is made optional it may die out as people fear being one of a minority wearing it, or being associated with being old fashioned or "unliberal". The last university referendum saw a massive majority vote to maintain it; I suspect and hope this one will show the same.
As mentioned above, if wearing an item of clothing or two is that challenging for people then perhaps they should re-evaluate their choice of university and whether they will be able to deal with the pressure of going there.
You say "the sooner they get rid of these traditions, the better"- I genuinely feel quite sorry for you that you have such a narrow, unappreciative view of Oxford's history and the value many see in its traditions. I do not hesitate in suggesting that if you have such a truly negative view that you would probably find yourself happier going to another university, perhaps one with no history/traditions/soul.