Are herbs and oils important in Witchcraft? If so, why?

Depends on what you are trying to accomplish.

I am too sensitive to scents, so I can't use incense, oils, and some herbs, but thankfully the Goddess doesn't seem to mind.

Some oils and herbs have been proven to have strong medicinal purposes. Healing people has been a very important and foundational part of Witchcraft sense man started the first fire.

Yes i think they are i cant do any workings with out them,i use them to correspond with my spell the day of week,moon phase candle colour ect ect.With out them i feel that the spell isnt as effective!

They are not essential but they are highly useful.

Yes, you dont want them witches getting hungry

It varies from witch to witch. Some witches use herbs and oils for their magical inclinations in order to help strengthen spells/amulets/talismans/rites/etc while some of us, instead, prefer to use herbs and oils in a more healing/curative manner (in fact, you'll find that many people who know a witch/healer will typically consult them first with an illness or problem before going through the hassle of going to the doctor - though if your witch/healer friend doesn't advise that you still at least talk to your doctor about what he/she is telling you to take then I advise you do so).

Then again, some other witches entirely prefer to place importance on an entirely different thing for both healing or magical purposes (i.e. crystals, stones, charms, candles, ritual tools, themselves, animals/guides, etc.).

How else are you going to cook the Witch?