I don't think the trend is exclusive to theme parks... Look around you. The world is changing.
Also, you're being a bit overdramatic and resentful of others who do visit Disneyland to indulge in all things Disney. The stores may be stocked with Disney merch, but there are still niche products at all of them -- from glassware to original art to magic to christmas ornaments to cooking items to silhouettes to candy. DL's Main Street may no longer sell tobacco products, bras, or greeting cards, or have a real photo shop (in an age of smartphones) but what they do stock in the stores (beyond the Emporium) is still of a pretty wide variety. Is it all Disney focused? You bet it is. You're in freaking Disneyland, not Crate and Barrel.
What exactly are you hoping to find in these stores?