Like many other writers, I pay too much attention to my rejection letters. I like to get the personal notes and feel temporarily devastated by the say-nothing forms. The personalized say-nothing macros, while no more informative, provide an indication that the editor doesn't think the writer is clueless. Personal rejections mean that the editor likes the writing, but that the story didn't work for that magazine. It may sell elsewhere.
Personal rejections are the next best thing to a sale.
Targeted form rejections are used in almost every case by Marion Zimmer Bradley. These rejections, while not personal, pin-point a specific problem in the story. Her set of rejection letters can be entertaining, after one has gotten over the initial disappointment of failing to sell. It's more honest. First, this is a buyers' market.