Basic service is very much what the old FIS did. Part of the problem appears to be that in the past people asking for a FIS got a bit more, for example if they were talking to a radar unit they might get some traffic information. This inevitably led to inconsistincy in the service being provided which in turn might have led someone used to flying in a particular area where traffic was routinely passed to expect the same thing elsewhere.
The new regime attempts to standardise things so what you get is uniform, regardless of where you are.
Like the old FIS users of Basic Service can use it to get the RPS, ask whether Danger Areas are hot or cold, check frequencies, get clearances etc etc.
Like you I fly a non-transponder equipped aircraft and therefore tend to listen to London Inf and only talk to them if I need to.