It's particularly prevalent at this time of year, with people warbling on about Merrrrrrrry Chrrrrrrristmas, the Chrrrrrrist child, holly berrrries etc. Yes, I KNOW the theory is that it's necessary because the R sound is weak, but really, that's a load of nonsense, isn't it? No-one seriously thinks they're singing "Mewwy Chistmas", do they? And singers in musicals etc manage to make themselves perfectly well understood without doing it.
It was brought home to me today on listening to that version of "Walking In The Air" where adult Aled Jones duets with a recording of himself as a child. Young Aled, as a well-trained choirboy, trills on about drrrrrreams and frrrrrozen strrrreams, whilst adult Aled has plainly learnt better and sings like a normal human being. And actually adult Aled comes over much more clearly without all those intrrrrrusive R sounds.