The impressive thing about Dharma & Greg was that although Greg played the straight man, he was never played as silly, and he never broke character. (Actually, there are a lot of impressive things about Dharma & Greg including the psychology; it is entirely believable that Greg would "rebel" against his parents by marrying this impulsive chick who then turns out, what do you know, to be rather more like his own mother than her own. And it is entirely believable that Dharma would decide that her soul mate is a man who can give her the stability she never thought she had, and in some ways really didn't have, in her own home.)
Frankly, Jenna Elfman just isn't surrounded by that good a cast. I like Dabney Coleman; I think he is hilarious in You've Got Mail. But Dabney Coleman can't do all the work. Dharma & Greg had two sets of extraordinarily gifted and funny actors as the parents. Also, the writing was better. It's too bad, since Jenna Elfman deserves another hit.