There are some actual facts on this thread and some complete bollocks too
The speed does to some extent rely on the distance from the exchange,also the cable conductor size and in some much rarer cases whether its copper or aluminium.
It states up to 8meg, not that it will be
BT have never been allowed to lower prices due to restrictions placed upon them or to roll out some technology that has been available to them for some time. All this was done in the name of fairness to other operators who doubtless would never want or have afforded to maintain an obsolete and decaying network.
You may or may not have heard about something called 21CN, this should hopefully make the copper based PSTN and ADSL technology a thing of the past and bring speeds up to a level unseen before and also make VOIP the way we communicate in the near future
I admit BT have made mistakes especially with their customer care, but when you have a workforce decimated by over 50% and the ever present pressure from the city and shareholders to make more profit its no wonder something had to give.