Everyone wants an excalibur sword for their tool at work; I think most lisps are more like hitachi vibrators precisely for the reasons you say.
I'm sure lispworks, corman and the rest of the proprietary lisps have some cool GUI tooling and other useful practical bits nobody in open source common lisp land wants to build (instead preferring to fuck around with yet another compiler). Of course, so does Delphi or any other proprietary language. The real key to developer productivity is someone did the shit work for you and wrapped it in a useful way.
I'm sure lispworks, corman and the rest of the proprietary lisps have some cool GUI tooling and other useful practical bits nobody in open source common lisp land wants to build (instead preferring to fuck around with yet another compiler). Of course, so does Delphi or any other proprietary language. The real key to developer productivity is someone did the shit work for you and wrapped it in a useful way.