From Charles Shadwell on Facebook:
That's a crying shame. However, I think it has to do with the fact that she doesn't have any single outfit that the majority of Sci-Fi fans readily associate with her, unlike River who has that distinctive dress-boots-sword-and-axe combination. It's a pity that the leather outfit pictured in your post wasn't actually worn by Cameron in any of the actual episodes, because it IS distinctive (in a good way too), and she was rarely seen in her prized purple leather jacket, which had the potential to be memorable as well. My best friend (who's a hardcore Scf-Fi geek and lover of TSCC and all things Summer) said she wanted to dress up as Cameron for Halloween in past years, and she did as far as I remember. But she did say that it was difficult to make it obvious as to whom she was supposed to be without using makeup and such to signify the 'Terminator' aspect of the character. So I suspect Cameron just never wore a single, distinctive outfit long enough during the show's run, whereas River was consistent with her flowing dresses and boots.
I think it's safe to say that Cameron has made a decent, measurable impact on pop culture considering TSCC's ill fortunes: Cameron is what most people liked and remembered from TSCC, at east in my experience, and she's always featured prominently in any major list of 'badass' female Sci-Fi characters, most especially robots/cyborgs - doubly so when it's gynoids specifically. Also, Summer is a lot more well-known now - she's earned the title "Queen of Sci-Fi", and every article quickly brings up her role as Cameron, and always in a positive tone. Cameron is like the show that birthed her in that she's a tragic, monumental waste of potential, practically an embodiment of the maxim 'the good die young' - but she still made a respectable impact considering all the adversity she faced.