I'm exactly the same spot as you're in.

Previously i'm a Network Engineer working for an ISP.

Now working for an MIS company, as a System Engineer.

MCSE is as important as CCNA. What you'll learn in Networking has gotta be going somewhere right? Operating System comes together with Networks and vice versa. You'll not be going anywhere far with just knowledge in Networking only. If you're only good in networking, you'll stuck for being an engineer only. Eg. laying network cables, setting up wifi, etc. And no company would employ ppl to just sit in the office and plan for networks You'll have a brighter future if you have both. And now since your company focus more on Windows Server, might as well take advantage of that and go take up MCSE and you'll be ahead of your colleagues