The current license allows only reproducing the code for reference use without modifications. Using a more permissive license such as GPL or AGPL you could benefit from the improvements made by other people. As the project seems not to be maintained currently, this is very important for those who wish to continue using this software and keep it updated.
I have myself done several improvements to the EppaBasic code but, sadly, cannot publish these under the current license.
The current license allows only reproducing the code for reference use without modifications. Using a more permissive license such as GPL or AGPL you could benefit from the improvements made by other people. As the project seems not to be maintained currently, this is very important for those who wish to continue using this software and keep it updated.
I have myself done several improvements to the EppaBasic code but, sadly, cannot publish these under the current license.