At first glance, the Trump plan has two very good reforms.
First, it solves the main cause of the “problem of pre-existing conditions”—tax policy that rigs the market in favor of employer-based health insurance—by equalizing tax structure for business and individuals, thus opening up a vibrant individual health insurance market that will lead to health insurance being as portable as auto, life, and homeowners insurance. And it will attack the high cost of insurance by knocking down inter-state trade barriers to true, national competition among insurers (a power that the Commerce Clause of the Constitution gives to Congress). Both problems are the result of prior government market interventions, and which ObamaCare disingenuously sought to “fix” by piling on more government controls, rather than repealing the prior controls.
The Left will hate this program, because it leads to less government control and more individual self-reliance. The only kind of “plan” the Left will accept is one that empowers government masterminds and forbids individuals from planning for their own healthcare. If less government control and more individual self-reliance is what Trump means by “make America great again,” it’s a good sign.