What made the variable geometry (swing) wing design feature obsolete?

For a good while, swing wing was the flavor of the day and everyone wanted some. Then, the feature completely vanished from the “generation” of planes that followed.

What made the design attractive enough to be used in the first place? The feature added a lot of weight and electro-mechanical-hydraulic complexity to system and jacked up the price too but still, the feature was implemented. What made it attractive?

And finally, did the advent of FBW negate the advantages of the swing wing?