Absolutely right. Upgrades and adding features is one thing -- I can choose not to use something that is newly introduced. But automatic and irreversible changes to the appearance of the content that we have created according to old parameters is unacceptable.
Evernote should respect their users right to preserve a style of working that their own software has helped them formulate. Any changes should be options, not fiat.
Users have the right to a simple unformatted note!