User blog comment:StrategicMagic/The Most OP Item in League of Legends is.../@comment-4593717-20130407032545

This is all true, and all of the Doran's items are truly powerful in the early game. What they don't do is:

1. Build into other items

2. Scale well into late game

Therefore, they are very strong items in general, but because of their inability to carry forwards, they aren't overpowered at all, or even in need of nerfs. Also, they are not restricted to a single group of champions (like can only be purchased on APCs), so everyone can share in their strength, regardless of role (exempting maybe supports).