Actually, I think it could go the opposite way (more people buying more Lightning Lanes). My family lives out of state, so when we go, we do pay extra for things to help maximize our time vs. waiting in line. When I pay day by day, I will buy Genie+ in the beginning of the trip. But as the trip goes on, we often end up riding most of the rides through Genie+ or standby early in our trip, so we don't really need or purchase Genie+ for all the days.
Now, that I need to plan in advance and can guarantee that I can reserve rides we want and at times we want them, we are more likely to purchase more Lightning Lane days so we don't lose the opportunity later. When planning any WDW trip, my husband and I usually plan for more and then cut back our plans once we are a few days into the trip. (Don't mean to do this, we just think we can accomplish more than we actually can before getting tired.) This will likely lead to us overestimating how many days we need Lightning Lane. I can see other people overbuying this too.