I'm interested how you can manipulate ratings in the upward direction if minimum ratings were included in the criteria? Certainly there wouldn't be a reason to bag your rating.
Isn't the most common "manipulation" of ratings to quit a round so it won't be counted (prompting the 888 code)? My understanding of why people quit to "save" their rating is so it will move or remain higher than perhaps it should be. Needing a minimum rating to play Worlds might lead to more 888-worthy DNFs.
Frankly I don't see how or why minimum ratings will ever be a necessity for Am Worlds at least. It's not really in the best interests of the organization to make any change to Worlds qualification criteria other than raise the minimum points. If players need more points for Worlds, they'll play more events. More player means more player fees taken in which means more income for the PDGA budget. I would think ratings minimums would have the opposite effect...players attain required rating and sit on it until Worlds rolls around.