Ok,
is a caster ADC, so saying he should have DPS other than damaging abilities is unfair since that's his thing.
was always good with
cause of her ult and generally you don't build DPS on her cause her ult is her thing.
is either going to almost 1 shot a squishy because of armor pen or the 800+ crit he gets with the help of his Q. Nothing really changed in his damage output from armor pen from what I've seen.
is a bit tougher since he's newer, but the only big difference I've noticed is with armor pen he spends more times flashing in to get that last auto instead of ulting to kill you, and either way it still does the same 1200 damage.
Now, I completely agree that it's insane that getting hit by an MF Q bounce, losing half your health, and then having the duskblade pop take you down to near death is completely broken. However, there are some ADCs that use some of those items that would be hurt without them. MF with BC, Twitch and Quinn with ghostblade, most ADCs with Lord Dominink's. I personally find the ADCs build path to be rather sad since you almost always buy the same items in every game without little change. At least the armor pen meta brought out some different paths even if the items were being used for not their initial purpose.