Grievous Wounds, considering the limited options to apply it like Executioner's Calling and Morellonomicon, isn't an acceptable answer to lifesteal. EC would be great, but the stats on it blow donkey nuts.
I find it somewhat ironic that you call Riven broken because part of the underlying problem is that building lifesteal on her is extremely effective while getting a massive shield. She heals herself while not taking damage off her life bar. If you think Grievous Wounds solves everything then play Renekton with an EC and win every time.
I will concede that, yes, lifesteal by itself is not the problem. (see Riven example above). You (Seven) are correct in saying that building CC is the answer...when you apply it in a specific scenario in your head ala "just CC the ADC and kill them." The problem with the current meta, and this I believe is hardly arguable, is that bruisers are really strong right now because of the new defense masteries. Most bruisers will build one lifesteal item, mostly a Ravenous Hydra. The thing about that though is that teams in general are all becoming tankier. In addition, Leona, Taric, and Thresh all became top tier support picks overnight. My point here is that ADCs, while weaker in a 1v1 matchup with bruisers, are enjoying much much more CC and peel in team fights with a team that knows what they're doing. This also means it's much harder to apply Grievous Wounds to them because it's harder to get to them and stick to them.