Why does the Coin, the lowest gmp support starting item, have the best active?

To me, there seems to be a disjunction between what the purpose of buying coin is, and why people actually buy it.

It's supposed to be the "lowest risk, lowest reward" of the three choices. Of course, supports that can't harass well are meant to buy it. But sometimes you want to get coin simply because the active is so much better than the other two. Why are supports that choose frost dagger punished with a worse active, while those that go the "low risk" route get the best active?

It's just that each time I support I have to ask myself, "Does my team need the Coin active?" which kind of defeats the purpose of choosing your starting item based on its gpm. Why not make it so that you can choose which active you get by buying an enchantment for your starting item. That way, you can still go the high-risk-high-reward path without having to be stuck with an active that's not as good.