The vim bindings are only one part of Spacemacs. The other (and I'd say most important) part is the SPC menu that exposes hundreds of keybindings in a discoverable, unobtrusive, and interactive interface.
The keybindings are bound with evil and displayed with which-key, but the spacemacs special sauce is the keybindings themselves. There are probably thousands of them across all the optional layers. They're crowd-sourced essentially. So you don't have to set them up manually for each language/tool you work with, you just add the layer and get sensible defaults out of the box.
I guess so? And if the aim is to make something completely custom, that's fine. But the Spacemacs keybindings are very well thought out, the configuration is just as important as the feature itself.