I think "Flashback" made it perfectly clear that an Excelsior series using the elements from TUC would have sucked hard. Takei's not a brutal actor or anything, but his performance in that episode didn't exactly scream "make this into a series!" for me.
On another note, I seem to recall an episoe in which a ship commanded by someone named Captain Sulu dropped of Chakotay,as a boy, and his father somewhere.
I do agree, Takei taking the captain's chair probably would not have been as exciting as someone else.