It's a holidays bucket, so they can sell cheap fares to get leisure punters in, while the G fare will never sully a corporate travel agent's books. As a result, with most of the cheapest buckets sold out, they'll still be getting decent revenue out of busniess travellers booking in economy - even with a weekend stay.

V fares will never be used as an advertising tool but it does mean that golds can book with miles even if there is no other avios availability - although with a cheap G fare available, it's questionable as to whether they should.

T fares probably aren't that cheap - the Q bucket for dual inventory fares seem to be sold out, and with limited advance purchase requirements, they probably won't be advertising-worthy either. On the other hand, they can be used by people who booked a T fare months ago and now want to book onto another flight (after flying the outbound, they'd only pay the change fee) and they will certainly be on the cheaper end of what a premium-economy travel policy might sustain. So it's another indicator of a fairly quiet flight: I don't think I've ever seen a completely full WTP cabin when T was available shortly before departure, but they don't ever get that empty, either.