What both Graham and Pete say above is true - each though representing the arguments looked at from either end of the spectrum.
As a DCC user, it seems crazy to introduce 'under-spec' devices, but as an affordable Christmas gift, it gets DCC into the homes of the masses and gets the kids keen on DCC.
Remember that Hornby is a public company and therefore, to satisfy the marketplace it has to announce a couple of big developments each year. It has to be seen or perceived by investors at least to be leading the way. An entry level system now, a middle of the road system later and perhaps a top-spec system in a year or two. I'm sure they'll do it.