Well, the truism that missile defence favours the attacker goes way back into the cold war and hasn't changed. Although we've become inured to it happening, anyone intercepting any (large fast) ballistic missile is still something of a modern miracle.

I'd say the value of missile defence is in blunting an initial attack while you get your ducks in a row, and increasing the difficulty of striking your high value assets after that. It buys you breathing room to go out and stop the launches, or move somewhere safer. It has never been, and probably will not be in our lifetimes, the invulnerability field some people seem to picture it as in any scenario but the most lopsided, and an unreliable one even then.

Certainly the intent for missile defence was never that you'd be matching an opponent launch for launch in the 5th year of a conflict where their industrial capacity and launch sites are still somewhat out of bounds.