Lulu is toxic for more reasons then "running after you" or "she can shield". A lot of people really dislike playing against a lulu and probably if the meta wasn't filled with uber strong carries, we'd see more bans for enchanters like her.
But in general though, enchanters, particularly shielders like janna and lulu have been incredibly too powerful for the longest time. They don't really have any cost to using their shields so they can pretty much passive the entire laning phase (or with lulu, aggressive) and negate any and all poke. You can't really lose lane with an enchanter unless you overstep into a hook or binding, or the ADC/enchant gets too aggressive. At least with an enchanter like soraka, she breaks down from paying her own health.
That being said, just the fact shields can be this strong, and stack up with locket + the champs + aery + bloodthirster + overheal is a little ridiculous. Toning it down by this little is just a step in the right direction.