I thought the same thing and in testing dismissed the idea.
My example has 50k documents, frequently a specific type ahead text will have several pages of identical or similar documents. So hiding it would prevent access to whose documents.
My case there may be 20-30 with the same first column and different info in the rest of the columns. If the first column values were all different, I would probably use a standard single column dialog rather that the picklist with more columns.
Perhaps , if the picklist had a scroll bar and showed all the hits, not just the first x documents, then that may be OK.