Certainly a fun playground for local climbers year round.
I commented elsewhere when they were still mulling this over last summer. Sounded like a sure thing politically to make local tourist industries happy.
Compared to our other national parks, the monument is quite small at 40 square miles, about 10 miles long averaging about 4 miles wide. Some might think that is in any case rather sizeable. However the actual area of the geological features where all the trails are is far smaller, maybe just 4 square miles. Could trails expand into those peripheral areas? Sure but those landscapes are rather ordinary much without outstanding features. In fact much is chaparral that has burned over the decades in periodic wildland fires. Those peripheral areas are valuable to the park's wildlife so have value but not as outstanding or unusual scenery any more than other parks in the region or Los Padres National Forest. California has an abundance of small area features in state parks, national forests, and on BLM lands that would rate well in national parks. However unless such features are part of a larger regional set of outstanding features, I don't think raising them up to national park status is wise.
Like much of the inner Coast Range, the Pinnacles is really only pleasant during fair weather periods of late winter and spring. Its seasonal streams flow, grasses and wildflowers are nicely green, and its creatures are out and about. By June anything green other than trees has turned dry brown with daytime temperatures often as unpleasant as in the adjacent Salinas Valley. And most of its creatures other than birds then only venture out during dawn, dusk, and evening hours.
Although it is true making PNM a national park would increase its tourism value, nearby Point Lobos State Reserve, the 17 mile drive on the Monterey Peninsula, and Big Sur Coast state parks all have higher natural scenic and interest values. It would increase numbers of non-Californians and international tourist visits but I would expect many of those visiting outside of spring will be disappointed reducing their confidence that those areas we designate as national parks are worthwhile visits. Another similar park in the Coast Range is Carrizo Plain National Monument. Absolutely incredibly World Class with vast wildflower displays every few years or so during wet years for a brief month or two and then long periods where it is hot, dry, baked, dormant, of low interest and not scenic.
Can just imagine local motel and businesses in August pushing foreign tourists playing golf on the coast to drive inland and enjoy a wonderful noon climb up the trail at the new wonderpark. Then listening to them cuss later that evening in a bar at their cool coastal hotel about taking out dried stickers stuck in their sweaty socks.