I agree. When we began cruising and it was basically Caribbean and Bahamas (one was Alaska), if we wanted an excursion, we did book
DCL. Most of the time, we walk around.
However, when I started planning the British Isles cruise, I noticed that DCL didn't always have what I wanted. We like to tour on our own so we booked a few DCL excursions, and a few private excursions. And to tell you the truth, the private ones were far better and more flexible. However, unlike what I've read in some of the threads, our private one were more expensive than the DCL excursions. But I will definitely say, the extra cost was worth it.
So for our Norway/Iceland cruise, I booked only 1 DCL excursion and the rest were private. It is nerve wracking trying to choose the best ones, so it's not easy. But we would prefer certain experiences and sometimes DCL doesn't offer it. They are wonderful in offering the popular sights and activities, but a lot of them are geared (at least in my mind) for less active experience.