Play kitchens help kids learn how to be cooks or chefs, roll play cooking for themselves and their familiies, etc. I'll go one step furthur and say that baby dolls can help little boys learn how to be good Daddies. Play sewing machines and irons can help boys learn how to be tailors. Toy cars help kids learn how to be good drivers. Blocks and toy trucks help kids learn how to be city planners and architects.
All of these life skills are important for all children.
All 3 of my children had a variety of toys as preschoolers: dolls, balls, toy cars and trucks, pretend household items, blocks, etc. My girls gravitated towards the dolls more than DS did, and DS gravitated towards the cars more than DDs did, but all 3 kids did play with all of the toys.
If your DH is concerned that a pink plastic kitchen is "too girly" for a boy to play with, then get a nice wooden one instead- or at least a plastic one in bright primary colors. Not that little kids care about colors or gender stereotypes anyway, and I remember reading somewhere that about 200 years ago, pink was considered a "manly color" and women never wore it.