I hear what you're saying, but if there were benches "here and here and..." there would be 3 people sitting in each one and many more people who wish they could sit there and are upset that they can't.
I also wonder if the decisions of where to put benches, and how many, are affected by how people use them these days. 20-30 years ago you'd have a bench and someone might sit down for a few minutes for a brief rest or while they wait for a family member to come out of a restroom or shop, and then they would move on. Now, if you provide a comfortable place to sit, those spots will be taken more quickly by people, including younger people, who will use them as a parking place to use their phones to check email, text, etc. You see how long people hang out at tables at quick service eating places, even if there are people looking for tables so they can eat. The number of people who would be able to use the benches would be so minimal that it is hardly worth having any.
I would hazard a guess that with the number of scooters running around the parks these days, there are more people sitting down in the parks than there have ever been. And those scooters and the Cadillac sized strollers many people use also take up a lot of space.
I really don't envy the task of the people who have to come up with the plans to accommodate all of the foot and vehicular traffic (and parking spaces for the vehicles) in a lot of these fairly tight areas. I really don't think the evil motive of getting people on their feet to spend more money shopping has anything to do with it.