Talking about going to a 50/34 chainring set and then changing the cassette to make up the lost gears is a red herring; because as others have pointed out, you can change the cassette out by itself, in which case you wouldn't be restoring lost gearing you'd be increasing your present range. Many people find that they have to shift the front more with a compact, because there's less gear overlap between rings.

I regard compacts as a half-solution where a full solution already exists.