[_coveredInBees]

Not exactly. "Extend those wrapper libraries" is not at all trivial or easy because when the wrapper library / charting library creates abstractions, it also places some limitations on the overall customizability. So when the wrapper or charting lib isn't cutting it, trying to shoe-horn the feature you need is not always easy and usually involves ugly hacks that reduce the overall simplicity of the code if you had just rolled your own D3 implementation from scratch.

[jordache]

The difference is between tweaking the wrapper library or write everything from the ground up because one can not deal with tweaking the wrapper library.

Pros and Cons with both approaches no doubt.