By lay definition Consumerism reflects the activities of all consumers in buying necessities and fulfilling our needs through the purchase of products. These purchases support our economy that should support infrastructures and the well being of our society, reaffirm our civilization per say.
Planned obsolescence is a vital component, these days, in the design process. The design of a product is given a predetermined life span for the use of the consumer. The packaging of a milk carton is designed to maintain the contents in excellent condition, under refrigerated conditions, for a period of time that extends past the use by date of the product.
On the other hand, a mobile phone, or perhaps an electric fan, might be given a reasonable life span of five years or less. I feel that the ethical issue is that the failure designed in the design might be based on a practical premise like, people will not want to have a mobile phone longer than perhaps two years, as they will want to keep up with the technology and update their phones as often as every six months. Based on that premise a life span of five years would indeed be reasonable.
In an economy where people within the society build an expendable budget into their lives, this concept is not really a problem. However, for those with limited resources that need technology to earn their meager living expenses, may need their phone to last them ten years.
I have fond memories of the days when one could purchase a Transistor Radio, a Valve Based Television set and even an Electric Fan, with the confidence that these items would run reliably for many, many years with very low maintenance requirements. This is not the case these days, and I am confident in my view that the failure of goods these days is through no failure in design, component strength or any other over sight. Sadly, the ramifications in terms of pollution are obvious, if we take a glance at at what our throw away society does with our out dated computers, laptops, CD Roms and other numerous items. Throw away phones for example.
My perspective in summary is, planned obsolescence can be integrated into a design with ethical considerations included as an important component in the design process. It is when the design includes forms of obsolescence that are based on reasons to simply increase consumer spending to raise profits for individuals and/or companies the question of Ethics and Fair Practice become a very important factor to consider.
This is my opinion and I hope it helps your thought process.