*This Section Contains Spoilers From an Internal Leak*
To use Secret Invasion as an example, there are indications that several super-powered individuals (hero and villain) have been replaced with Skrulls. What's more, those people have in fact been Skrulls since some point in the 70's. For these characters, this means undoing every single bit of growth they've had, since before that point, characters didn't evolve over time.
Luke Cage has become, over the last few years, a father, husband, and leader. He's gone from being quite literally a Blaxploitation character with low-key powers to a potential leading man for Marvel; powerful enough to warrant a place on the main stage and developed properly as a man who could lead the Avengers (which he has been). Nope! Not anymore, because Brian Michael Bendis really likes the old version! Ergo, we get stuck with a guy with no depth, and we're expected to swallow the fact that Iron Fist, Luke's best friend nearly since their debuts, had not noticed, and that the impostor had decided not acting like the guy he'd replaced would be the perfect cover (especially with the getting married part). It's just dumb, and it injures all the stories that feature Luke.
Short version: events like this all end up being one kid in the playpen messing with everyone's toys, and I for one wish that we could just have some time without all this nonsense. At least, I'd like it if Bendis would stop taking all the toys and making a huge messy pile.