In answer to your 3rd paragraph we are still the same club, they are not. We have only changed grounds, they started a new club at a new ground.
Their loyal fans fought to stop them using the name Wimbledon, Hence the Dons,
MK Dons have never competed with the big boys.
you are referring to AFC Wimbledon, and many other football fans the country over would love to see them competing with the big boys again.