No, I don't think so. This kitchen doesn't have them and it looks just fine:

You may not need the molding, but it would definetly make the ceilings look better. I like the idea of keeping with your craftsmen theme on the windows and doors. Find a simple crown like this one https://www.houzz.com/photos/5-star-green-bungalow-traditional-kitchen-austin-phvw-vp~91600 The molding will help draw the eye up and make your house look bigger with taller ceilings. Just my thoughts, have fun building your home.

I think yes. Attached is a photo I took seconds ago of my living room. It is a blend of colonial/craftman. My wife and I now laugh when we remember that we hesitated about spending 3K on the ceiling coffer trim. It makes the room and is the first thing people say they love when they walk in. I am a big believer that trim work makes a job great when building blended traditional homes.

Thanks very much for your responses. I really appreciate all of the input. The photo of your living room trim is beautiful. Do you recall the actual moldings you used? Including the casements. We've had a really tough time finding more simple moldings along the lines of craftsman style. Thanks again.

I used all MDF trim and millwork since in knew it was going to be painted. I also used a really good painter 3 coats oil based semi gloss enamel sprayed and sanded between coats.

Window trim is flat 1x4 jamb trim and bottom with 1x stool extending to outside of side trim. 1x6 at top over 1/2" head casing sill. All edges are sharp. I only have butt joints in my house except for the crown molds. No mitered joints for me. I use butt joints for looks and because they show less separation in older craftman houses that have foundation movement.

Doors have 1x4 jamb trim with same head casing sill and 1x6 at top with 8012 mitered crown and 1x top plant. I only used the crown and top plate at selected doors and windows. Doors at 1" thick 12" tall square base blocks that align with the 1x4 above and my 1x10 base board buts into the side.

The coffer is 1x12 sides, 1x6 soffit, and 8012 crown.

Beautiful with the trim!!!! Takes it to another level!

Whenever possible always add architectural detail, as long as you are not taking away from the height of the ceilings...you do not want to feel as if the ceiling is coming down on your head. It is detail and the simple items that make a room a castle.