As retail has become dominated by national chains, they have gained leverage over suppliers and demanding deeper discounts, longer payment terms, and instituted a variety of fees, fines and discounts they will simply deduct from your payment when they feel justified. As a supplier, it's very frustrating. There is little if any opportunity for a supplier to negotiate.
Some suppliers react by choosing not to accept these terms of business, and that's their prerogative. My suggestion is that they not do so emotionally, but rationally consider their choice.
In my experience I have always found that more distribution is better. You'll make more on some transactions than others. But unless the smaller margin transaction is literally taking away larger margin potential sales, I'll still go after it as long as the revenue justifies whatever sales effort I have to put into it. It may not be true for every product, but often, the more places a consumer can run into your product, the more you will sell.
While there are certainly cases where the pricing and other challenging policies demanded by a retailer makes selling to them less attractive, I have yet to find a situation where I lost money instead of making profit by increasing my retail distribution.
Although sometimes I scream at retailers in my head, I try not to let my annoyance at their demands cloud my judgment on whether I am better off making the sale or not. To the "small guy" it may seem predatory, but they're just trying to get the best deal they can, and in today's world they are in a position to do so.