If we were all deeply pessimistic about redeveloping software then we might still be using VisiCalc.

Sure, redeveloping software involves costs and risks, but so does running a business on a software system that's hard to support, hard to enhance, and fragile.

If redeveloping software (with an existing system as a guide) is such an onerous undertaking then where does anybody find the intestinal fortitude to develop software in the first place?