Final answer:
Complexity is not a factor of successful product and service design; whereas cost-effectiveness, aesthetic appeal, and customer needs are key factors for a product’s success in the market.
Step-by-step explanation:
The factor that is not a determinant of successful product and service design is D. Complexity.
While cost-effectiveness, aesthetic appeal, and customer needs are crucial for product design success, complexity is generally not.
Indeed, complexity could be a drawback, as products that are too complex could fail to meet customer needs effectively or could over-complicate production and use.
In contrast, cost-effectiveness ensures that the product can be priced appropriately while maintaining a profit, aesthetic appeal can differentiate a product in the marketplace, and customer needs are fundamental to ensuring a product's relevance and value to the consumer.
Assessments of design quality often focus on whether the product hits the right balance among these attributes rather than on adding unnecessary complexity.
Failure to adequately test prototypes or ignoring the evolving consumer tastes can result in design decisions that don't resonate well with the target market or make the product impractical.