Wouldn't this find of richly dressed bodies refute the long held notion that the early Christian religion appealed mainly to the poor and slaves in Rome??
Possibly, but not necessarily. Dressing a corpse was in some ways like vesting a priest: a symbolic and sacramental act. A single wealthy patron could have paid for burial clothing for 1,000 people of much more modest means, just as Joseph of Arimathea, a wealthy man, supplied the burial place and arrangements for Jesus.
Read the old classic Fabiola (Lepanto Press) to get an idea of how both wealthy and poor were early Christians in the catacombs. Both lived and died for the hidden faith.