These systems aren't sold on usability, but on cost, regulatory compliance and compatability with other database/billing/communications systems.
We've just got a PACS system - allegedly costing about $50k per workstation. It's without question the worst system I've ever used. The vendor states they designed it with reference to 'several' doctors - but you'd be hard pressed to tell.
I've never seen a system that is so difficult and clunky to use, the tools and mouse controls are so counter-intuitive that I still struggle a bit even after a year of using it every day - heck, they've even modified the text boxes (for entering search info) so that they work differently to normal windows textboxes. Not just that, but the system is horrifically unstable, although after a year of use, they've finally patched it, and it's sligtly better - prior to the patch, workstations would need rebooting about 5-10 times per day (hard reboot, not just log off windows), and the servers (remember this is potentially a life critical system) would crash and need rebooting once every week or so. Even after the patch, the workstations still crash once or twice per day, as well occasionally corrupting doctors' written reports, so they need to be redone.
If you think I'm joking about the textboxes, I'm not. I thought I was going mad because I normally touch type to fill in windows forms, using tab and other keyboard shortcuts, but I was ending up typing gibberish, because selection and editing worked differently. To prove it to myself I ran a code decompiler on the software and found the offending behavior modifing code.
Oh, and then there's the problem where when reading X-rays and preparing the written report, it'll bring up the report editor for 1 patient and the X-ray for another. This one is a bit of a problem, and I thought I was going mad when it first happened to me, but I reported it and heard nothing more. 6 months later, there was an 'urgent' 'critical risk warning' sent around, saying that there was a problem where occasionally the report editor may not match the images being displayed. So, there was a patch to fix this? Nope. The circular said "Workaround: All staff preparing reports should check that the name on the report and images match before saving the report".