Does a mother of the groom need to defer to the mother of the bride on dress choice?
No. You are equally important and have every right to pick the dress that makes you feel fantastic! Most brides we talk to today prioritize the personal preference of the moms over asking them to match—each other, or the bridesmaids. It's always a nice gesture to ask, and align on degree of formality or, if it's important to the marrying couple, a general color family. Take mother of the groom Jane—her son and daughter-in-law's only request was that the wedding party and family not wear solid black. And Jane always gravitates to black. She compromised in this ombre gown, which satisfied the couple and allowed her to feel like herself, but elevated.
My biggest obstacle in looking for a Mother of the Groom dress was the over abundance of sleeveless dresses. In my mid sixties, I want my upper arms covered at all occasions. (Perhaps that’s the reason so many of us resorted to little jackets with sequins.) I managed to find a dress with sleeves, but it was very difficult! You provide a great service! (I saw a very similar dress to mine worn by Sara Ferguson as the mother of her princess daughter.)