Tldr; What your'e saying is factually and statistically wrong, and obviously so.
[{quoted}](name=Master Summoner,realm=NA,application-id=3ErqAdtq,discussion-id=GyvOUikU,comment-id=,timestamp=2017-06-12T10:51:01.538+0000) u all just used to how he once was and now suck with him now perhaps.
Perhaps, why not just scream to the rooftops that you have no experience on this subject and don't know what you're talking about. At least try to hide the fact if you're going to try to force your opinion on someone as if it were fact.
Not only that, but the last time you played Rengar was two weeks ago and you're only mastery 1 on him. You have to at least play the champ to be able to make the statements you are making. Like how you said he is fun, or how you can say anything about his old kit versus his new kit.
As for whether he is decent, here are the statistics:
lolalytics- 47.48% winrate jungle, 47.42 top
lolking- 43.5% winrate
leagueofgraphs- 46.7% winrate jungle, 46.8% winrate top
champion.gg- 48.25% winrate jungle, 50.03% winrate top
na.op.gg- 49.07% winrate jungle, 49.1% winrate top
I'm going to count lolking as unusable(since support and mid are in that number as well), so the average is: 47.875% winrate jungle, 48.3375% winrate top
Both of these are considered fairly low(although top is borderline decent). So you're a little wrong there.
Statistics aside(because that would be a scarecrow fallacy, you having mentioned whether he is decent), that is not the reason people are asking for changes. They are upset because he doesn't feel like Rengar anymore, his thematic and kit no longer matches, and they were promised he would still be an assassin(which is a large part of his thematic) but they changed him to a diver. You can see how upset people are with it by his playrate, it has dropped from 10% to 3.5% [league of graphs], 2/3 players just don't play him anymore.
A thematic of someone who hunts down powerful creatures, tracking and chasing them down doesn't fit with jumping into a battle and waling on them as they wale on you. His thematic suits a play-style of jump in, do a lot of damage, get out, if they aren't dead wait to pick them off in a bit. The complaints about his ult I have seen is that it also contradicts the thematic, you can't sneak up on your prey if they know when and what direction you are coming from, its just going to make them run away losing your chance to get them, it's now more of a herding tool strategy wise because of that. I also know there's a lot of complaints about his Q, but frankly I don't know what they're talking about, haven't played old or new Rengar, only against(at least one of us can admit that). Same thing with this aoe assassin stuff you mentioned, no idea what it's about, haven't even seen any people complaining about it befo