Cutting fees and slashing ad prices would be a start - but it would take a while before people trust it.
We got into FBA heavily because it dramatically boosted sales... even on products we co-listed FBM on (nuts, you pay more to fulfill it via Amazon's network, but they boost your sales, so it washed out).
Recently, they've been increasing FBA fees to where it's finally at the point we're re-examining it's profitability and possibly moving back to FBM for 100% of our items. But... not everyone has the luxury of having their own warehouse and fulfillment infrastructure - a lot of Amazon sellers are vested 100% into FBA and are at Amazon's mercy with fees.
There are a lot of people in your boat and there are some companies that provide sophisticated software solutions to determining the best mix of FBA vs. FBM for your business.
I don't think that's necessarily true. Majority of products sold on Amazon are sold by 3rd parties. Amazon's commission fee structure, and seller-eats-return-shipping-by-default is to blame for prices going up on many items...
Competition among sellers is fierce on Amazon - and historically was a race to the bottom, chasing sometimes $0.10 profits after paying for shipping materials, shipping fees, labor in warehouses to fulfill orders - or paying FBA fees which are often higher but gets a sales boost by Amazon for the privilege...
Amazon keeps raising commission rates, FBA fees, sticking sellers with return shipping label fees, commission minimums, etc. It all adds up to an unprofitable proposition - or you must raise prices to compensate. So, that's what has been done... making Amazon more expensive in general for almost everything.
Sure, Amazon could cut their fees tomorrow - but it will take time to work itself out into lower prices for consumers... especially since people are unlikely to trust Amazon's fee-holiday longevity. Amazon tends to change things at will with minimal notice.
Do yourself, and small businesses alike, a favor - find something you want to buy on Amazon - then search the seller name on your favorite search engine. You might be pleasantly surprised with the free discount you receive by purchasing directly from the vendor's website than through Amazon + all the fees.