Paddy is right, the bino brands need to sell binos and not just in the first year of a model's introduction but continuously. They don't operate in a vacuum, competitors launch new or refreshed models which attract the attention of customers and sales can drift away from long-established models to newer ones no matter how good the older ones are. Brands respond to this by launching their own new or refreshed models.
You can see this operating on a wide variety of products, not just binos. A walk through any supermarket reveals labels on bottles of shampoo, toilet cleaner, washing-up liquid and many other products all carrying a flash shouting NEW.
New versions of car models are launched at regular intervals as the brands seek to keep them centre-stage.
The pressure to replace perfectly good product comes from the fact that competitors are doing this and getting their products reviewed in the media and creating a buzz and an excitement around their new product that generates sales for them.
None of this means that anyone who is happy with their Dialyt or original EL or their FL or BA/BN has any need to change unless a new model has features that would genuinely increase their enjoyment.