Look, the real problem is nobody is doing any 'strategic planning'. If strategy involves balancing ends, ways, and means, we stopped doing that about a generation ago. We plan, at best, campaigns and call them strategy. Having said that, I agree the process can be improved.

1. Anybody who thought that adding IPRs for senior leaders would quicken the pace of planning clearly has never worked in a US headquarters. Not only does it slow the process, it distracts planners from real work and serves to filter ideas (good, bad, and indifferent).
2. The process (to work as advertised) demands creative, flexible, thoughtful senior leaders, willing to entertain opposing views and unorthodox solutions. More importantly, those leaders must be willing to champion unpopular operational approaches in front of their bosses. Such men are in short supply. In fact, I would go so far as to say that in the majority of cases the involvement of senior leaders suppresses creative thought and promotes groupthink.
3. It always amazes me how people miss the link between improved tools for planning and slower planning. Remember, there is no such thing as a labor saving device; creating tools that allow for doing detailed planning faster doesn't mean you create plans more quickly, it means you can plan more details!
4. There aren't enough trained planners. This is why we continuously have to employ wandering ronin planners from organizations like the JPSE (an excellent and descriptive acronym, by the way). These 'pros-from-Dover' are great guys and very competent, but they lack the situational awareness and institutional knowledge to do more than produce boiler-plate in a crisis.

The author criticizes APEX as a bad process, but his solution is to replace it with a better process. Wasted effort. There is no process so good that the military can't ruin it. What we need are more leaders and planners who can think creatively based on deep and intuitive knowledge of the problem set they face. Until we have that, no process will improve the product.