Clerics were that all around class that wore heavy armor, wielded a mace, could take and dish out hits only second to the Fighter but when someone needed healing or that horde of undead showed up, he was there to heal and turn those undead. At later levels he stepped up with his call lightning, hold person, etc.
The thief was the go to guy when you were crawling through the dungeon. He kept the party safe finding the traps, opening the doors and when combat broke out he was able to hide and deal the big damage backstab if he was lucky.
Now a days it's not enough to play that specified role, we all have to be "equals" in combat. If the fighter gets big swings then by golly the rogue should be able to sneak attack every round, the wizard should be hurling flame bolts every round and the cleric should be flame striking everything in sight. It reminds me of the ADHD kid with sensory issues that cannot sit still and must always be doing something with his hands. Players are less worried about roleplay in combat because they have too many roll play options at their disposal. There are no more distinct roles because the cleric can heal, but so can the ranger and the bard. No need for the rogue because the fighter with the high perception can find those traps just as well. We don't need the wizard to identify anymore because we can just play with our new weapon for an hour, attune it and we know all we need to know. It's just all very generic now and I don't understand why everyone feels that everything has to be balanced.