Unhappy? Max out checked luggage
I almost never check a bag, even though with elite status, a Reserve card, and an upgrade, I often have a baggage allowance of 3 free bags.
Many people can't really leave DL either due to being hub captive, needing a particular nonstop, or corporate policies. So "voting with your wallet" can be difficult.
But what about expressing displeasure with recent changes by checking the max number of bags each time as a protest? Ideally these would be large old bags you don't care about, filled to maximum weight with junk (phone books, bricks, etc). Maybe the extra work on the ground, wasted fuel, and exclusion of other cargo due to weight limits will get the mothership's attention?
Just saying...