This article is about such issues, though. If you have a walled garden, you're basically trading your freedom, for the ability to have someone else police the software, to presumably eliminate such threats.
That trade-off's value is entirely dependant on the quality of the policing done on the software inside the walled garden. Historically, Apple's been pretty good about it, too. But with people locked into the ecosystem by their prior app purchases, there's less and less incentive for apple to spend resources keeping the quality control high.
This could be just a blip that Apple will correct, and start maintaining high standards again. But it could also be the point at which the walled garden deal starts to turn sour, and people find they've been locked inside a garden nobody's looking after.