The problem to me is that this is used too often as an excuse by sloppy developers to not care about the quality of the software. It is too easy to overlook the impact 6 months down the line of the lack of design/readability of some piece of software.

I have seen this too often. Technical debt is OK when it is managed. I.e. taking shortcut when we need to ship a product or reach an MVP in 3 months is fine, but having a sustainable software will require to pay back some of this at some point, or velocity/quality will suffer on the long term.