If you have very good knife skills, you can get more of the edible pineapple with a good knife - the corer results in about one-eighth to one-quarter inch left inside the skin. But it’s a tedious job, and I’m not good enough with knives to do it quickly and efficiently. I like the gadget ;-)
That’s very little waste!
Also, the thing that makes carrot cake and zucchini bread so good in my opinion is the crushed pineapple! In fact I wonder if I could just make a pineapple bread or pineapple cake. I really do love the stuff but don’t know very many recipes that use pineapple.