I didn't like the initial blonde FemShep they picked not because she was blonde, but she just looked so washed out. The pale skin + blonde hair just didn't look good together, or something.
Honestly? I like the new default. I'm playing as her now and the in-game model grew on me. Sure, on the CE cover she could look more battle-worn (and less left the salon) as MShep and use a bit less makeup but she's nice to look at. =P Patryk Garret's art of her (my icon) also grew on me. I guess I just like that battle-frenzy look she has.
As for Miranda, when I last saw Yvonne Strahovski I remember studying her face a lot and she has Miranda similarities. There's also the fact that since Miranda is 'genetically perfect,' her face is unnaturally symmetrical and that could be throwing people off. I think it makes her look creepy, myself.