I agree. I think Fanny and John are so unlikeable that for other characters to be different from them is an immediate favorable recommendation to the reader. John not only lacks the strong feelings of the rest of the family but he is something of the opposite being “rather cold hearted, and rather selfish” and Fanny is more of the same per Ch. 1. I do not think Mrs. Dashwood is overly emotional on that point about Edward—to be different from Fanny is to be the opposite of cold-hearted and selfish and the same logic can be applied to John and his step-family. As long as the characters are what they appear to be then this logic works out very well. At Barton a similar situation exists among the family. Sir John and Mrs. Jennings are boisterous, warm hearted and generous although inelegant while Lady Middleton is “perfectly well-bred” the Dashwoods find her “cold insipidity… particularly repulsive” in Ch. 8. It is no hardship for me to like the first two despite their faults just as I like Mrs. Dashwood and Marianne in spite of their willingness to cultivate excess sensibility. (:D)