"Necessary" is a fun word.

Have we, to date, printed anything in our 3D printer that helps us deliver Git repositories in a quick and timely manner? No.

Have we built something that kept 140 employees happy and excited in the company because they're exploring technology they hadn't used before? Yes.

Have we built something that helps everyone at the office learn and understand a major technological shift that might be useful in the event we'd like to build a product around this in the future? Yes.

Is it fun to print cool shit? Yes.

So yeah, I'd say it's necessary, at least for us. It makes the company a better place, both from a cultural and a business perspective. Your mileage may vary, naturally.