It took a few weeks for Evernote to answer the question. But it turns out that Evernote only cares about new or 'light' users: "The web version is made available to our customers based on account usage. More specifically, the total number of note created on your account. The current cap is 10,000, which includes notes from shared notebooks, public notebooks, spaces, or those creates over the 12 years you've used Evernote." It's a realy strange way of treating your most loyal customers. I'm using Evernote since the beginning and I have more than 15.000 notes, so I don't get the new web-version.