Is modularisation really an answer or is this another case of "A Hundred Authors Against Einstein"? The reason why many people are still driven to Amazon is that dealing with separate entities is just annoying as hell. Small business is definitely less reliable than Amazon and even if client service has been declining, it's still has a predictable baseline. Product search also seems to be working much better in Amazon than in web search engines. If I have to choose between one average retailer and 100 better-and-worse retailers, then I will still use Amazon.
Also - the long tail exists almost exclusively on Amazon.
Also - the long tail exists almost exclusively on Amazon.