There is no reason to not enforce the idea that children need to face the world for what it is outside of the classroom and for that not to be mandatory. Perhaps it shouldn't be difficult or unattainable or cumbersome but it should be mandatory as per a certain selection of trips and topics instead of a set number at a set date for every student else they risk a lower scoring.
There is a strong difference between reading about something and actually witnessing it and this is why I suggest it is so.
When we say requirement, it has to be needed, to be of necessity, and to be of an importance vital to the subsistence of one thing. Educational trips sure have lots to give to students but then, it being a requirement would defeat the purpose of having a school. Schools should provide the students with templates of the real-world so that they would not need to go to dangerous places while they are still under training as professionals. When we require educational trips, that means teachers have to include it, whether they like it or not, and students have to go, whether they like it or not. In my opinion, educational trips can be alternatives to learning but it should never be "required".