The one angle that has not been explored as much is the overall trend. Let's go ahead and assume that wood pulp is a safe thing to consume, it certainly seems to have no nutritional value whatsoever. So why are companies inserting it into food items? To mask inflation and earn more profits most likely. This was a major theme I focused on last year in a series of pieces on stealth inflation and food fraud, a couple of which can be read below:

New Study Shows 59% of "Tuna" Sold in the U.S. Isn't Tuna

New Study Shows: Food Fraud Soared 60% Last Year

The Quartz article notes that:

There may be more fiber in your food than you realized. Burger King, McDonald's and other fast food companies list in the ingredients of several of their foods, microcrystalline cellulose (MCC) or "powdered cellulose" as components of their menu items. Or, in plain English, wood pulp.

The emulsion-stabilizing, cling-improving, anti-caking substance operates under multiple aliases, ranging from powdered cellulose to cellulose powder to methylcellulose to cellulose gum. The entrance of this non-absorbable fiber into fast food ingredients has been stealthy, yet widespread: The compound can now be found in buns, cheeses, sauces, cakes, shakes, rolls, fries, onion rings, smoothies, meats—basically everything.

The cost effectiveness of this filler has pushed many chains to use progressively less chicken in their "chicken" and cream in their "ice cream."