Note: Current Romania never claimed to be a descendant of the Roman state, unlike those other countries you mention. Byzantium was actually the valid successor of the Roman Empire, since the Romans themselves made it and it was a splinter of the former empire. The HRE, Russia, the Ottomans, etc., were all claiming the former Roman imperial glory.

Instead current Romania was named as such just based on the endonym (the name they gave to themselves) of the locals: Romanians. The name of the locals does imply a connection to the Romans, as their descendants, but that's it.

What I'm trying to say is a bit subtle, but basically Romania is a name which acknowledges a fact (the Romanians are descendants of the Romans/Latin speaking populations; not even our greatest enemy, Hungary denies this), not a claim to greatness. So the name is a logical extension of this fact, just like you'd call the land of the Greeks, Greece (or the land of the Albanians, Albania) :)