I'm in two minds, too. Seems like a cheap ploy to push listeners onto digital, when DAB is still far from ideal and few people are clued up enough about radio being available on Freeview, Sky and FreeSat, because for years the shops have ignored radio services on these "digital TV boxes" (and unless you have your sound wired separately, it's a waste of energy to have a TV on just to hear the radio services).
piprabbit - there will no doubt be links from the R4 pages at www.bbc.co.uk/radio4 to the 'R4 Extra' pages, and you'll be able to hear the programmes via the web, if you have no other options such as DAB or digital TV box.