There's a significant difference between providing a tool to allow an end user to take an action and leveraging your position as a middleman to inject content. This is no different than the egregious behavior displayed by Verizon and others.
What gives Ad Block Plus the right or qualification to determine that my ad is a "bad" ad?
Why should ABP have the ability to suppress editorial or advertising content on my website, replace it with it's own advertising content and not share revenue with me?
Ad blocking itself may be considered a ethical issue as well, but it's a different ethical issue. With blocking, the decision is ultimately made by the end user. With ad injection, ABP is making itself a third party stakeholder.
What gives Ad Block Plus the right or qualification to determine that my ad is a "bad" ad?
Why should ABP have the ability to suppress editorial or advertising content on my website, replace it with it's own advertising content and not share revenue with me?
Ad blocking itself may be considered a ethical issue as well, but it's a different ethical issue. With blocking, the decision is ultimately made by the end user. With ad injection, ABP is making itself a third party stakeholder.