I recieve around 18 D / 2 U FTTC. With the cloud becoming more and more important, why does a product such as 18 U / 2 D not exist for people that a) cannot move nearer a cabinet or b) afford a £20k leased line?
Just to elaborate on @witchunt's answer...
The VDSL2 spectrum allocated to upstream and downstream van be varied by the telco running the FTTC cabinet, but it has to be the same for every single subscriber on that cabinet. If you don't do this, near-end crosstalk (aka NEXT, which is different from the usual far-end crosstalk FEXT that most lines suffer from) will destroy the service for most people.
That NEXT destruction of the service is the technical reason for forcing identical allocation on every user.
In making a choice of the allocation to actually use, BT have to figure out what the majority need. The majority need 6-7x as much downstream as upstream, because the majority are watching video. And BT want to sell video.
BT therefore choose to use an asymmetric allocation of spectrum that favours downstream by around 4:1.
If you are amongst the <<1% who want an extended upstream vs downstream, then your needs are very much in a niche market, which is served by leased lines.