Our use of a trailer depends.
1. If we need to get there in a days travel and the miles to get there are over 500 miles then we consider using the trailer.
2. If we are going to stay for longer than 5 days we also consider using a trailer, (wife loves to bring the kitchen sink, and Neal's coffee pot to MV)
Oh and we bring our Canadian buddies tee shirts when ordered. etc etc.
3. Sometimes we just use the trailer because we don't feel like riding that route, case in point is going to MV as we have ridden over the roads there many times over and there isn't much to see, (just want to get there mentality). Also to RibFest for same reason, except we rode this past year, but will trailer next time.
We love to ride everywhere, (rode 20K on it this year) but I think there are times when you just don't want to for whatever reason so a trailer is a nice back-up when you have those moments.