I would have twin pod drives along with fore and aft thrusters if I could afford them. Why not?
Single inboard with no thruster and manage to tie up without drama but am all for technology and thrusters are hardly "the latest" tech. Fairly well proven, tried and true some might say. Go for it is my vote.
At best my Owens might support a stern thruster as I really doubt there's enough room for a tunnel out front. The external bow thruster would have a short life in my gunkholing area and too much drag penalty on my planing hull IMO.
As for a reason to install one... A fat enough wallet is the only justification needed for any boating related purchase, again IMO. That and they look pretty darn handy.
It's easier to fool people than to convince them that they've been fooled - Mark Twain