rolling your Rs isnt do or die … but it can help the listener … it does help with enuciation. I understand words much better in Welsh when the R is emphasised maybe because most of my life has been in northern Wales
From what Ive read in linguistics…the ongoing demise of R -rolling in Britain over the last 200-300 years, started as usual with much modern language evolution from the SE of England and London.
The reason is assumed to do with differentiating class/status reasons historically (The spread of received pronunication “Queen’s English” across the education system - Ive met people from shropshire who said they were punished being rhotic even until the 1950s
…you can still hear a few farming families even on the west sussex downs who slightly roll Rs but its basically extinct down there…same with R rolling pushed further west through the old West country…and up through Yorkshire and Lancashire (similar advance to the word mum replacing mam/mammy in most of Northern Britain now