In 1859 the 2 Principalities Moldova and Wallachia united, and formed the United Principalities - the official name.
But the goal of the romanians was the creation of "Romania", the romanian state.
Though the United Principalities were recognised officially, the name "Romania" was not, and the romanian politicians' goals were to obtain the recognition of the unification under the name "Romania", and obtaining independance under this name.
The smaller powers, like Serbia, were ready to recognize the new state under that name, but the greater powers were not. Because the recognition of the United Principalities in their view did not mean recognising their independance too.
The great powers were ready to recognise the new name "Romania" on condition the new state retains its vassal condition, and its lack of independence.
So the romanian politicians refused the compromise, and so the recognition of the official name of "Romania" had to coincide with obtaining the full independence. It was a political decision, because if the political compromise would have been chosen "Romania" would have come into official existence in 1859 or shortly after, but it would not have been independant.
I hope I was as clear as possible, looking back, it does look a bit unclear. If you want something better clarified, please feel free to ask.
take care
Considering your vast erudition, I just assumed you were American.
Since then I'm pretty much trying to recoup by using various documents and sources... 
