Outside of Amazon, Amazon has helped to set new standards for online commerce (free shipping, fast shipping, no/few questions customer service). When you see Zappos (now Amazon), Jet, Walmart, Home Depot, Lowes, and Ebay all mimicking aspects of the Amazon shopping experience, you're also seeing increased competition. It also has effects on brick and mortar commerce that are beneficial for consumers. Some stores match Amazon prices in the walk-in stores.

It has absolutely taken margin out of the retail industry, making it harder on retailers, but so long as they don't fail in droves, margin leaving the industry is money that's being returned to consumers, at least in part.