I’m convinced that this is not a problem caused by end-user cookie settings. It could be regional or a lot of things, but it’s not because of browser cookie settings. It doesn’t matter whether AliExpress maintains your login status or not; you still shouldn’t have to log in to view items or perform searches; that’s a requirement made by the server and is either a feature or a bug.
Though not an improvement, I’m actually not terribly disappointed in the new item pages because they are less busy, but things just don’t work as well as before and there’s simply no good reason to make people log in to browse your store. It’s not so much a privacy issue for me (it’s no trouble to track your browsing in-between logins) as it is an inconvenience and matter of principle.
Having seller messages disappear does take the cake and would put me off of AliExpress pretty quickly. Except for the recent PayPal issues, I’ve had a flawless buyer experience on AliExpress to date and even had productive conversations with sellers, so I hope that this trend doesn’t continue. I actually liked buying from AliExpress and don’t see any similar options that aren’t more expensive.