Complaining about Riven in 2011 vs now
2011: Most champions in the game are fairly immobile, a champion with high dashing potential and overall mobility is an absurd thing, it landed Kassawin in 90% pick or ban rate. Feast or famine champions are not standard, there are a few, but none scale harder than a fed Riven. On top of that, good base stats, high HP regen and insane bully power leave top laners of the time - basically stat sticks with no mechanics - with no way to outplay her. Riven's end up crushing lane unless they are awful. Overconfidence of real Riven mains makes those who aren't good more arrogant and toxic. She is badly designed because she doesn't fit in a game full of low mechanics stat sticks who win through meta-gaming of buying better items and winning through gold, gold and more gold.
People complain about Riven because she doesn't fit into the game and therefore is situationally overpowered. Mostly justified.
Now: Riven's base stats and numbers have been nerfed multiple times, she has no more HP regen at all essentially. Every new champion has an overloaded kit and a simple stat stick hasn't been released in years. Most primary top laners counter her such as Jayce, Gnar, Kennen, Darius in low to mid tiers, Garen in low tiers, Renekton, Rumble situational, Camille unless you are god-tier, Cho'Gath, Fiora, Kled, Kayle, and even some off picks like Trynd, Akali, Morde and Rengar. Dozens of champions have equal overall mobility to her, some have more even if circumstantial. Feast or Famine is the standard for fighters, bruisers and top lane carries and several scale just as well as a fed Riven. Overloaded kits with too many shields slows, CCs, Tanking Steroids and burst damage despite having DPS are the standard, not the exception. CotC is slightly overpowered on Riven but it is also slightly overpowered on other people who abuse it, mostly junglers. When it is nerfed she will be too.
People complain about Riven despite her having an atrocious win rate in Bronze through Platinum and animation cancelling not even being a major factor until high tiers where she finally becomes viable in Diamond and slightly overtuned in master.
Conclusion This is very confusing for me, perhaps people are use to complaining about Riven. But in this day in age, Riven is the standard, and low counter-play, low-option stat sticks are becoming the exception. As the game advances to be more based on skill rather than gold economy.
Do I like the direction of the game? Perhaps not, perhaps so. But it doesn't change that Riven is no longer the only mobile, strongest scaling, feast or famine champion she was. I can understand complaining about Riven in 2011, but in 2016, moving onto 2017. It seems silly to target her exclusively. Whether it be newer fighter/tanks like Vi. Newer 'skirmishers' like Ekko, Yasuo and Fiora. Newer junglers like Elise or Ivern. Newer top laners like Gnar. Or old champions who were fully realized like Jayce. Everyone has bloated kits these days.
And just to name other people who can easily escape ganks top lane but are strong when they all in and have generally bloated kits:
prenerf
The old School of OP
The old School of OP

If you haven't got it by now, this is the direction the game is going. More towards reflex, skill and interactivity, out with stat 375 beats stat 373 because it is higher.
P.s This doesn't mean I think all of these champions are perfect in design. But they are the new direction regardless. Even Darius takes more skill and has built in options and counterplay now.