Daphne believable as the object of such idealization?

It's only Nile who actually called her a goddess and I think he's really into skinny women :)

I hate Tarantino

Well.. it wasn't as if it was Seattle that thought/regarded her as a Goddess, it was spindly, meek, henpecked Niles.
The women he had been with Maris, Mel etc.... were far from attractive.

I have known people with average looking spouses that worshipped them as if they were super models.

I thought she was very pretty in the face in the early days. I did kind of notice that as far as her figure she is kind of straight up and down, but I've known a lot of men who like long legs just as much as big boobs, something about the image of those legs wrapped around them is what my husband and brother-in-law have told me. I think women with curves and breasts are more attractive, but I am not a man and I'm not a lesbian so what do I know. A lot of supermodels are pretty straight up and down and a lot of men seem to like them too. The funny thing is while I at least thought Daphne was pretty in the face I never thought Roz was all that attractive and didn't understand how she got all those men. I chalked it up to her being easy.

"Really her face is mediocre to me and she's flat chested"

a) only my taste matters
b) the 50s are back

Look at the sort of woman Niles married. When you think of that and stack it up against the sweet and funny Daphne I should think you could understand why Niles thinks she is a goddess.
You may feel that Sofia Vergara or Megan Fox are goddesses. That is your idea of a goddess.
Not everyone would agree. We all have our ideas of what is attractive and what isn't. That's not bad!

Happens all the time... People fall for all sorts, they fall hard...

For most of us, the person we come to fall in love with and adore more than anything else, maybe even at first glance, will likely be fairly average to most others, because odds, so yeah, I'd say it's realistic.

Plus, given what we heard about Maris, outside the money, she'd be an easy act to follow.

Niles himself being unimposing and not physically aggressive, it seemed like Daphne was a logical fit for him.