The downside of just making offers is that they’re not useful on their own. People on your list won’t receive any value from you unless they buy what you’re promoting, so they have little reason to stay subscribed. That’s why this email marketing strategy doesn’t work alone. And it’s why many e-commerce sites struggle to keep people interested. There are a few exceptions (e.g., Groupon) that rely entirely on making offers—but then the reason people joined the list was specifically to receive those offers.
Great companies are always evolving, and your customers expect to experience change. What they don't expect (because too many companies haven't lived up to this end of the bargain) is to be told about those changes. That said, this email from ModCloth serves as a refreshing change of pace. If you're going to change the way you communicate with a lead or customer, give them clear, fair warning so, if they aren't on board, they can make the necessary adjustments to keep their inbox clean.
When you share your opinions, avoid dipping into politics, religion, sexuality, and other topics where many people have almost fundamentalist views. If, however, you know that most of your audience shares your opinion on a topic that’s important to them, you can instantly seem more trustworthy by pointing it out because people trust people who are similar to them.