Not all Russell Group Universities are worth much. They only survive because of the RG label. I agree that some non-RG universities may actually be better than certain RG unis.
I think there should be a change in the structure of Russell Group. There should be three tiers:
1. The Big 8: Cambridge, Oxford, Imperial, Manchester, LSE, Edinburgh, UCL and Kings College London.
2. Russell Group
3. Non-Russell Group Universities
To the OP, i think focus is moving aware from where you went to school. Except certain jobs like probably Medicine or Law, most employers don't care about whether you went to Cambridge or Southampton.
To people, i suggest that you attend the "best" university that you can possibly attend. Dont waste yourself studying a mediocre course in a dead-end university.