I wouldn’t say that a blazer is an essential thing to have in your wardrobe, but if they fit you well and you pick the right style, they can look very good. And they can be very versatile. They can be matched with a pair of pants, a skirt, or even shorts. As for color, you can go for something neutral so as to be able to match it with any other color. Brown is fairly neutral, and can be combined with a surprising array of other colors.
All three of these are very nice, I think:
Left: MAXSTUDIO DOUBLE BREASTED JACKET
Middle: 11 FOXY Womens 3/4 Ruched Sleeve Boyfriend Blazer
Right: SJSP Women Plus-Size Single Breasted Fitted Blazer Jacket