abc and Thistle have said this already, but I'll repeat: there's nothing inherently wrong with black shoes and grey pants (I do it!), but with your lighter hair, it might look less 'intentional' unless you add black somewhere else in your outfit.
Here's my take. Style is all about looking intentional. Colour is a part of that. I really think you can wear just about any colour combination and look stylish, as long as it fits with who you are (authenticity again!) and looks intentional. It doesn't mean that everybody is going to like it. We can never get everybody to agree on everything! But I think we all recognize style when we see it. Don't you?
Back to the shoes. Navy and burgundy are both less expected than black -- so they look more intentional, like you've chosen the colour thoughtfully -- and softer, which works better with your low-contrast colouring.
I popped over and looked at your other thread (sorry, I missed it the first time) and I'll add red footwear. You probably won't take me up on it, because red makes a pretty loud statement -- but oh my, red shoes + grey pants looks smashing to my eye! Especially if the top is neutral too. And red shoes ALWAYS look intentional.
Burgundy is a more muted version of red, and also looks fab, while being a little less flashy.