I don't think anyone could argue that having skills in both areas isn't a good thing. I've been a sysadmin for 20 years and i've had to do basic development over the years (apache modules, ldap-ifying applications, etc). When it comes to troubleshooting complex problems as a sysadmin and the whole team is whiteboarding, you can tell pretty quickly who understands how systems work below the user interface. This is often only learned through writing code.
The opposite is true for coders too. With a few execeptions, the most competent developers I've worked with have had sysadmin duties at some point in their career. Not that long ago, I had to sit down with a Sr. (Java) developer and explain load balancers and TCP session state.