Ah, I think I understand now.

In most cases, you will never, ever use 200 watts of amplification, no matter where you cross over the speakers, and no matter how loud you play your music/film.

That extra power is there not for extra loudness or extra bass, but basically for extra protection of your speakers. As I said, in most cases, you will never never need the extra power: however, occasionally (like in a cymbal crash or movie explosion) you need a lot of power in a hurry. Without the extra power, your amp clips and sends a square wave to your speakers, which will probably damage them.

So having the extra power means that your speakers are much less likely to get that square wave.

Jeff