I think you're underestimating her weight, most numbers I found (researching the stats for this tourney) put her more in the 140 range... though in some pictures I've seen I'd guess even higher. I wouldn't call 34D "meager" - but I found several sources that put her at 34E (DD)! Kate's certainly a big women - puts me in mind of the late Anna Nicole Smith BTW, so I'm not underestimating her in this Sexfight Tournament (she was playing for me last year and I credit her "vote sucking up" capacity for a large part of our team's success. Fanboys love to vote for her in just about any kind of poll!
Freeones; updated June 2018 ,has her weighing in at 130lbs and sizing up at 34D.
Boobpedia; updated July 10, 2018, has her weighing in at 130lbs and sizing up at 34H. (Perhaps recording her at her largest)
Healthy Celeb; updated July 26, 2018, has her weighing in 150lbs and sizing up at 34DD.
Celeb Health; updated December 2017, has her weighing in at 141lbs and sizing up at 34DD.
And Body Measurements; updated 2018, has her weighing in at 145lbs and sizing up at 34D.
Other Google searches yielded similar, with an average weight of 135lbs
+-5lbs, and a bra size of 34D/DD.
Baring Boobpedia as being an outlier and taking her at her bustiest otherwise, this isn't all that impressive, especially seeing as the average bra size for America is 34DD. So perhaps while it isn't meager, it is, as goro puts it, mediocre.
I'd say the majority of her appeal comes from her height and conventional popularity, which has in turn made her a favorite to win poll based fights, which in turn once more enhances her perceived catfight/titfight/sexfight prowess (I must admit she's often my default pick to win, especially if I don't recognize her opponent). This comes full circle as in cases where results aren't poll based and she DOES happen to lose, many often protest that she should have, citing her past experience and 'superior' stats.