Binders are useful for a number of reasons. Sometimes home processors can't figure out why they aren't able to get their bologna to turn out like the pros can. Often, it is because they don't realize the importance of a binder.
A binder will help to keep your bolognas smooth and avoid a crumbly, mealy texture. This will be more pronounced with larger diameter bolognas. It also helps to retain moisture and extend batch volumes. Retaining moisture helps to dilute the seasonings: If you've tasted bologna that seems overly seasoned, perhaps it was missing the binder.
Con Yeager bologna formulations usually specify binders. Leaving them out will compromise the intended flavor, texture, and specified yield. And because a binder helps to extend your batch, spending a little extra money on a binder can actually save you money in addition to improving the quality of your finished product.