While win rates are not an absolute, I do believe they mean more as far as viability (i.e. tier placement) is concerned than for other maps. Because champion selection is random, it removes a number of biases that might otherwise heavily skew results. Obviously not all biases are removed and there is always a margin of error but it's much harder than argue that, say, Poppy is more than maybe mediocre at best.
I rarely start without a Philo Stone on champions that use mana. Sometimes I'll start with it anyway on manaless champs if I have Heal. Starting Kage's makes sense on (manaless) AP champs and of course if you're building anything out of them, both Pick/Blade are perfectly fine starts. And please don't forget that they still do have other stats on them; you're not paying full price for gold generation alone, you're paying a small premium beyond the cost of a basic regen, AP, crit item. Philo Stone in particular is actually cost-efficient still, plus it's the only one that didn't get nerfed in Season 3 as far as gold/10 is concerned. ;[ Besides, ain't any different than Tear as far as trading earlygame power for lategame strength is concerned.