I agree, they lacked a little of imagination, didn't they?
But I've read somewhere that Tatiana wasn't common in the Imperial Family. Nicholas and Alexandra had discussed about this, and found the name beautiful, so Tatiana it was!
Must I ad that their people were pleased?
They weren't many Anastasias, either.
Oh, and their family actually disagreeded with their choice of Alexei's name, because it had been the name of a member of the Romanov Family that had had a bad end in old times, if I'm not mistaken.
A lot of of Imperial and Royal families did that, thought. Just think about Cleopatra's family: all their boys shared one name: Ptolemée! So they had a lot of nicknames.
And almost all children in the Windsor family, at least in the early XXe century, had Victoria or Albert in their names...