That is true. Considering it's no additional cost, I see no reason why somebody should go for a standard book. The timeline for producing both is the same, so is the cost. I'd rather get large passport book and use less pages than I need VS get standard and run out of pages, requiring to get new passport sooner (and pay fees again).
I had a standard passport from different country in the past. Used all pages and had to get large book from that country for additional cost about 3 years ahead of old passport expiration.