Many reasons as to why...I personally got burned out in the field, went back to school, got a computer science degree, and eventually landed in the informatics world.
I have colleagues who were really good at computers while working as nurses, and they were asked to help out, and eventually that turned into a job for them, and they liked it more than nursing itself so they stayed in informatics.
There are some who love computer work, and also are interested in medicine, so going for a nursing degree and informatics is one of the shortest route to kind of work in both fields.
And there are those lucky ones who were offered more money in an informatics position, and well, if you can't figure that one out, can't help you much.
But I've met doctors who as you can probably guess spent years in med school and then decided they would rather do an informatics jobs than practice medicine. Wrap your head around that one!
Now, you might be correct. There are many people who work in the field who have no clinical background at all, and like you said, they don't understand the priorities of what nurses do.
And that's the reason why you have nurses working in this field. They understand the priorities, workflows of nursing, and then from their prior nursing experience, they can help make computer documentation better.
Unfortunately though, many times you have computer applications that were developed without the input of clinicians and vendors many times would rather continue to implement what they have, rather than start from zero, and create a program that has a clinician's input. And that's why you might see an application that makes zero sense to use, and then you wonder, how can a nurse have created this crap? Well, response is, most likely it wasn't created by a nurse or with the help of a nurse, but now a nurse needs to try to make that application work for you.