Deeper Sibling Bond. Thankfully our girls have always played pretty well together. Even still, as we (incrementally) got rid of some of their toys, we noticed increased teamwork, sharing, and thoughtfulness with less greediness and wanting what the other person is playing with.
More time playing, less time cleaningup. With fewer toys, there were fewer tears when it came time to clean up time. The task of putting away their toys became less overwhelming because they were pulling fewer toys out. Putting toys in a closet helps TREMENDOUSLY with this.
Longer bouts of independent play. It is not uncommon in our house for the girls to play independently (but together) for HOURS (like 3, 4, or 5 hours+).
More in-depth play, longer attention span. My middle child has always tinkered well independently, while my oldest daughter would lose interest much quicker. She would play with her toys for a while, then stop, looking for the next thing to grab her attention. Now, she is much more engaged during her playtime. She experiences more focused, in-depth play because of this longer attention span.
More imaginative play. The girls will play dolls or dinosaurs, act out audiobooks that they have listened to, or play a character from a book or movie. Their imaginations are amazing! We have noticed that not having as many toys has given them permission to be creative with the props that they use.
Increased gratitude for the toys they have. They thoroughly enjoy the toys they have and get much more use out of them. As I am writing this, I am thinking about The Velveteen Rabbit and how wonderful it is that the toys my daughters own will actually become real.
Ownership. The girls take(much) better care of their toys. Why? Because there are less to take care of!
More content with their wardrobe; Less changing clothes throughout the day. When we had excess clothing, my girls would change clothes 4 or 5 times a day. Or more. I thought they thoroughly enjoyed changing outfits, but now I wonder if it was just their way of wearing alllllllll their clothes. I was hesitant to narrow down their clothes so much, but they have not once said they miss their clothes or trying them on. Now, we have only enough clothes for about a week. The girls have actually run out of clothes one week when we were particularly busy and messy!