I think I have said before on this thread, people are different, and have different needs and expectations, and what to take abroad is no exception. The issue here is whether Virgin should honour the expectations of passengers who booked in good faith - it seems they will.
I really don't think it's for others to criticise or question why people want to use their full luggage allowance - it's a personal choice based on personal need. The poster who wants to carry out extra clothes to leave behind is one example, we are getting married and need to carry out all of our wedding clothes, cruise clothes, wedding stationery, favours etc....We're flying with BA, and I would be very cross if the goalposts moved now when we booked months and months ago.
Good luck everyone flying Virgin - I hope it all works out ok