I think the curve of diminishing returns plays an important role. A near hack job will often get you 90% there, in terms of fulfilling what was exactly requested. I don't think this is true for any other skillset. It's so easy to make something featureful and fragile in software. The time and cost above that can be very difficult to justify to customers/management.
In the words of a previous boss, after I pointed out we need more testing, "Everything is working, we'll fix the bugs as they come".