You hit the nail on the head. Cognitive neuroscience -- especially WRT functional imagery -- reminds of the fable of the blind men and the Elephant.

(Very) roughly speaking, you have the choice between:

- Excellent temporal resolution & crappy spatial resolution (EEG / MEG)

- Pretty good spatial resolution & crappy temporal resolution (fMRI)

Other techniques (NIRS, TMS, etc) fall somewhere along the spectrum and have their own quirks. We're peering into brain function with a super-low-res "camera" and attempting to draw only the roughest contours of the thing we're exploring.