This is a very subjective question and judgement, as you see by the answers. What is "too much" to some is "just right" or even "not enough" to others. I found that once I got into working out with weights, I prefered a more muscular look than previously (that is, more than the "no muscle" look that graces the covers of some fitness magazines and was popular in the 60's). I'm not into vascularity in women, or extremely low body fat, and still prefer the Rachel McLlish, and especially Gladys Portuguese, look. In the early 80's, Gladys (2x wife of Jean Claude Van Damme) had what I think is the perfect balance of muscle and softness. She looked very feminine, as did many of the early 80's bodybuilders (who had bodies more like "fitness models" today). Another great looking bodbuilder from those days was an asian woman who had a similar look.
About a year ago, I happened upon a women's bodybuildiing contest while channel surfing, and the woman who won repulsed me! She looked like a man in drag. Got to have had some steroid help! The fourth runner up looked much better, IMO, but still "too much". But as I say, it's very subjective. I also prefer Cathe's look from around 1990, which still shows muscle tone, but is softer than now. That's the kind of look I would like to achieve.
As someone else said, to each her/his own! A former secretary in my department, who was a rather plump woman with no visible muscle (and lots of health problems because of a bad diet and no exercise or much physical activity beyond walking to the copy machine and back), once overheard a conversation between myself and a female collegue. The other woman mentioned something about shoulder pads, and I said I wasn't wearing any (all natural, honey!). The secretary said "those aren't shoulder pads?" and for a second, an involuntary grimace crossed her face. She was literally disgusted that I had shoulder muscles! Of course, from my POV, her soft, sloping shoulders were rather unattractive.