That would indicate that even at that point, their shields were far from spent. If that dish had been destroyed, the dialogs would have or should have been a bit different. That's impossible, while the bridge shields are low, the aft shields are still good- or something akin to it.
except Anakin DID get past the shield. I'd say shields do allow surface damage. It's just that no hit could reach the reactor with shields up.
Also a reactor could have addon shielding on the way.
Fighters in the SW universe can still have many missions besides cap ship engagment. If you insist on having a WWII ish analogy, look at WWI. Planes were more or less not up to attacking heavily defended targets, but they still fought in the war and attacked lightly (all things being realitive) defended targets.
During WW1, no commander would lead an attack of 20 planes against a dreadnought. No one would even consider it, and when ordered , would answer it is impossible. Planes were used for recon, and that's it.
Also, why was Needa terrified by MF flying towards his ISD? shields would stop it , or?