Nope, that knot is useful surprisingly often! It's the only applicable knot in that contrived single-handed-sailing-overboard situation, but it's also an effective knot when pitching a tent or tarp, or when hanging a clothesline, or when securing e.g. a canopy against the wind.
Yes, it's a great default adjustable knot! The other one I think is worth knowing is the "adjustable grip hitch", which is like the midshipman's but the half-hitch goes on the other side of the turns. This latter one seems to hold a lot tighter once dressed, even in relatively slippy rope, but unlike the midshipman's it can't easily be tied under load.
Taut Line Hitch is a little different from Midshipman's Hitch. Midshipman's grips a little better and is recommended. However, Like the other reply to your answer, for me the best of them is the Adjustable Grip Hitch. I teach knots to boy scouts, and know lots of them. After using the Adjustable, I don't use the Taut Line or Midshipman's anymore.
I learned it as the "Taut Line Hitch."