Emojis instead of dots — because it looks nice and has some personality, color, and meaning. Sunflower = MediaWiki, coffee = discussion, U.N. flag = translation, robot = bot, calendar = status updates, etc.
The character 🧩 is a puzzle piece, which is a common symbol related to Wikipedia. This character works on my machine, but emojis are sometimes displayed differently on different machines.
The triple globe in curly brackets is a symbol of "global templates". The curly brackets are a well-known representation of templates.
I think that these decorations make the navigation box cute and refreshing and don't hurt its functionality. However, I don't want to exclusively own it, so if you are very strongly bothered by it, feel free to remove these decorations. It's much more important to discuss the proposal itself than the emojis in the navigation box :)
(Also, it would be better to ask these questions on the talk pages. I only noticed it because @Ciencia Al Poder pinged me in on this page.)