Fan service didn't originate through Evangelion at all. Evangelion was probably one of the clearest backhanded slaps to the face towards fans. From Shinji being the face of shitty fans everywhere to "Sike! That's actually your
you're fantasizing about! HA
".
It just seems so odd in a show like Kill la Kill when everything - the action, the dialogue, the personalities, the abstract animation, the scope, and the setting itself - are so incredibly extreme that the sexuality would be something to be harped on. Its
supposed to be there. Its written around, commented on heavily, characters react, and it clearly appears to be a recurring theme in the show. Its very self-aware. That's the thing. I'm not even a fan of Panty & Stocking, but that show was basically Japan's South Park. I couldn't call that pure fan service either. Why? Because that's what its intended to be.
Fan service is when you're watching a show and in the middle of a more serious arc, there's suddenly a need for a trip to the beach and everyone has their cans out, posing. Better yet, when a character suddenly gets 6 more cup sizes. Or when you're watching Macross and a girl drops her cellphone into her lap right as she gets a phone call and has an orgasm right next to a guy she likes because why the fuck not. Or when a studio is given a great premise for a show and before it even gets to production there is a push to switch the majority of characters to women, turn things into a harem, and have them all as naked as possible while expecting to be taken seriously - which is entirely different in KlK because even the main character can't take herself seriously while wearing that shit. (Which is funny because they work with this a hell of a lot better than Yoko in Gurren Lagann who was fighting in a bikini just because reasons).
I agree. But that's generally... vague. There are things that people don't like, but there are definitely varying degrees of 'wrong' when it comes fan service.