I've noticed from what I've seen of White Collar & Leverage fandoms, people really seem to like the female characters in the OT3s (Elizabeth and Parker, respectively), as opposed to other fandoms where people are a lot more ambivalent about the female characters (e.g., they may like them in theory, but they don't like how they're written/portrayed on the show). So part of it might be about perceived improvements in canon depictions of female characters, aside from any fandom trends or developments.