AFAIK LH and the other members of *A moved from SVO to DME because the service at DME was much better than at SVO. Even SU decided to build a new terminal because even they could not get a better service. I do not know how the service is now at SVO, but a few years ago a terminal change from SVO1 to SVO2 could take several hours if you didn't want to pay the Taxi mafia and there was no way of checking the baggage between terminals (But that is now off-topic).

BTW: a friend of mine was flying HHN-VKO-ABA RT just a few days ago with VladAvia. All baggage had to be taken upon arrival at VKO and she had to queue again at check-in in VKO in both directions. No way of checking-through or getting the boarding passes to the final destination at the start of travel.