>>2982157Well first and foremost good UX work is difficult and time-consuming. And therefore expensive, if you're selling the software, since it costs not just the salary of a UX guy or three, but it delays your releases while they do a bunch of A/B tests. I'm sure the more paranoid management types are concerned about this user testing tipping their hand to other companies about what they're doing.
Second the people who build software have a much different idea of what makes a good UI than do most people that use software. Pretty much always, whatever the area. The UI always seems perfectly logical (or at least acceptable) to the dude who wrote it. That's especially evident in the open-source world - if you spend your days in bash and need to know sed and awk and a gorillion command-line switches for gcc, then complicated interfaces don't intimidate you. "It's a complicated task, of course the interface is going to be complicated!", you think. "If they can learn to do the complicated task, they can learn the complicated interface, of course."
Finally, back in the closed-source realm of ERP and such, companies probably just don't feel too much competitive pressure to improve the interface. It's difficult and expensive for a business to ditch one of those software packages for a different one. If there is a different one to switch to, even. I wouldn't put it past some of these companies to design their stuff so as to generate consulting fees for customizations.