My SQL developer schooled me on this recently after discussing custom query SWQL vs creating new resources. Apparently the resources are hardcoded to read from dll's and while its possible to create simple resources its not easy to guarantee that the underlying tables or code doesn't change in upgrades. So after doing both I can say I have gotten far more mileage from SWQL and benefit from knowing that they generally code in backward compatibility into the SWQL schema so underlying table changes do not always break code.
The turning point for me was realizing I could do node icons and links in the SWQL resource- I would like to have better documentation on what other visuals are hidden in there or could be added- bars like interface utilization uses, % signs, and alternative line shading.