The failure of Virgin Little Red's connection is not a reflection on the attraction of Heathrow it is more to do with the size of Virgin/Delta's offering from Heathrow.
Heathrow is operating on record passenger levels and is still the busiest airport in Europe so it must be doing something right.
I regularly travel through Heathrow and I find it delight to do so. I also like Amsterdam but not Paris CdG or Frankfurt.