Yes, but park days become cheaper later in a trip. For the first 4 days, you're paying over $100/day for even a value-season base ticket. But after that the price per day drops steeply. If you go from a 4-day ticket to a 7-day ticket, you'll pay about $70 more total for the additional 3 days.
If I'm taking the time off work, paying hundreds of dollars for flights, and staying onsite for a week, I'm going to be really upset if Disney tells me I can only go to the parks for 4 days, and the entirety of my guest recovery is a $50 refund per ticket.
On the other hand, if Disney essentially lets me convert those 3 unused days into a 3-day ticket, I can use them on another trip within the year, or apply the value of a 3-day ticket towards the purchase of another ticket.