Hi Max,
the title is part of the full text. This is fully intentional. Having RowIds as titles and thus as part of the full text is not a good idea. Especially if you create document vectors for classification. In the next release (6th Dec. 2017) we will release a new feature for the Strings to Document node that allows to create document with empty title. You will then have the choice of using a column, the RowId or an empty string as title. This will solve the problem that if you have no column to use for title but don't want to use the RowId as well.
Cheers, Kilian