Hasbro's not going to do anything about it - toys don't come with warranties, and as long as they outlive the expected use cycle (which is maybe a few years, for most toys these days) parents won't complain and thus it doesn't affect their bottom line. In fact, toys that wear out may well improve it, since it incentives buying new ones rather than passing on older toys. That said, I doubt it was a deliberate planned obsolescence choice by Hasbro, but rather a cost cutting measure. Cheaper materials keeps their profits up.
G4 is likely to have /more/ issues than G3, and those issues will show up sooner. We've already seen plenty of evidence of this.