When I built my RV-8 over fifteeen years ago I, I was living in Houston and flying back to Minnesota to visit family several times a year, often in winter. I grew up flying there, and new that a cold soaked airplane (that had sat outside) and battery were no fun to start - and if you cranked enough to get it started, you often had hurt the battery! So I I installed a Piper external power plug that could be used for an external jump start - not for when the battery was dead, but just as normal ops when it was cold so as to get a quicker start, and not use up battery life.
Since then I have built four more airplanes, and while they all have shop power connections (I usually use Andersen plugs), none of them have the capability to jump start because I don’t visit in teh far north in the winter regularly enough in any of them.
Bottom line - if you have a need for using external power at jump-start levels, a Piper plug is very handy. If you are just looking to power the airplane for shop work, you can easily get by with something less.
Built what you need for your requirements.
Paul