I hear what you're saying Marge, but I'd dispute that the 'r' sound is new. It may be increasing in use perhaps, but that often happens to a pronunciation. The 'r' has been long present in many accents, specially to the west of England. I often quote the lovely Lancastrian waitress who asked us if we wanted 'pepperrrrr on out pizzerrrr.' And I've already mentioned the Bristol 'l' which arrived in much the same way (though has yet to catch on elsewhere).
As for your 'muddled and careless' point, this again is no more than linguistic evolution. Once 'wright' and 'rite' were pronounced very differently, but no-one calls this conflation careless now. I'm personally saddened by the loss of 'brought,' but I accept why it's happening.
RP was evolved for social reasons. BBC English was born out of it, but it's adoption was for a different reason. When you are broadcasting to a poly-accented nation, they felt a need to settle on a from of speech that most would understand - and to an extent that is still true. If you want to be understood by those who do not share you 'natural' accent, it makes sense to make conscious compromises. But that does not mean that the adopted accent - which will itself evolve over time - is any more 'right' than one's own.
It's not even a class thing, necessarily. Note the silent 'h's of 'an hotel' (in Bayswater) and 'an 'otel' (in Essex). And also untin shootin fishin and shoppin.
(~M~ I think Bert was joking).