Managers always think that they are smarter than coders. Lets face it if they admitted that we could make business decision well there wouldn't be much need for them.
Also, yes - anybody can do management, and anybody can do coding. Learning to do either effectively is a skill.
Are you just making these decisions off the top of your head? Or are you talking to people, having research done, soliciting feedback, etc? In the latter case, congrats, now you're a manager! :p (If you're at a small company, you've probably still got enough time to do some hands-on work too...)
IME bad technical managers don't occur at any higher frequency than bad engineers; I haven't worked in other industries to know what it looks like there.
But you get a lot more immediate pain working for a bad manager than next to a bad engineer...