Some small percentage of those qualified for New EXP will think that it is great and some small percentage of those who were Old EXP and will not be New EXP, will either scream that they are jumping ship and either jump ship as the case may be. The rest don't spend their lives obsessing on this stuff and travel based on factors such as price, convenience, and the like, or they travel based on whatever it is that their admin books for them.
It is also a fallacy that AA wants everyone who does not qualify for New EXP to jump ship. There is simply a limit to what AA will do for people.
Finally, while MP and SM are not the same as AA, they have similarities and both of those programs are changing over time. One can't simply jump ship in a vacuum. Or perhaps one can choose the best flights for you and not twist oneself into a pretzel for not that much in return.