Yes, as a tank you can't really sit in the middle of the enemy team and take a nap anymore. You cannot afford to dive a turret with 5 champions under it and wait 3 or 4 seconds until your team catches up with you.
But you also get to deal a crap load of damage back. The changes went both ways. It's not only for the enemy team. As an adc now you can afford one tank item without loosing much in terms of DPS. You can even fit another semi-tank item and still hit hard.
Mages can have tanky items and still deal some considerable damage quite easily.
Assassins were even put into the play style they should have (well, kinda). If they time their actions right, they can one shot people in a second. If their timing is messed up, they get cc'ed and one shoted as a result. And yes, I'm ignoring tank assassins, this is a different problem caused by bruiser items.
The old times were never really balanced. You'd have the tank meta that could sit under the turret and 5 man focus and survive for a long ass time. You'd have assassin meta, in which assassins would instantly delete anyone from the game. Now we have damage meta, in which everyone can cause mayhem if properly built.
League is not a static game, part of the fun is finding ways to adapt to the constant changes. If we ever get complete balance the game will end up losing much of it's appeal and would become a glorified rock-paper-scisor.