What is a good kit design and what it isn't

Looking to the new patch I was suprised looking to zac( the old patch) and tristana: New mechanics!?!?!? this means new way to play a champ, new things to think while you are playing, more satisfaction while you are playing! THis is a good example of kit design. All the spells are linked to create a strategy or to express the typology of a champ ( look to Nidalee, an hunter who has a kit focused on chaising, perfect!). In this way, riot, you are doing great things and you have a good feedback from me. There are some other champs that lack of mechanics, they don't have an identity! (cough Evelynn cough). For example Rengar and his kit: he doesn't have a good kit. He has zero synergy between the spells, zero mechanics, but just press qq and only if you are in a brushes ( and an enamy is in range) or you are using the ult, which has a great cd for a great part of the game. For me to play rengar is thinking: q-q, I must wait the R to do what I want, throwing the bolas ( miss because I'm noob )q-q, waiting again for R. Nothing more. Riot from the point of the storyline rengar is amazing, the model is amazing! The gameplay isn't, because he doesn't have mechanics, he is an hunter with something like zero chaise potential, slow and with tank stats boost !??!?!? ( generally useless in this game and despite this boost he sucks in the first clear of jungle) I know, I know Riot wants to trasform him into a bruiser but an ultimate with stealth of an hunter doesn't fix the role of a fighter. And then there are too many fighter that can do this role better. So rengar for me is just a series of high numbers, nothing more: you press q and they die, maybe More mechanics riot! how you are doing with champions like zac, tristana, nidalee, sion. This make the game more fun