From a legal standpoint, a written agreement is far more better than an oral one. As others have mentioned, a written agreement can be easily defended in court and can solve disputes quickly. with an Oral agreement, you get into the grey area of I said and he said. Which are not easy to solve. Therefore, I have usually believed that a written agreement is necessary to prove the terms of the agreement between parties. On a different note, all regulatory agencies only believe in written agreements. If it is not documented, it never happened. for example, you cannot go to a supplier and establish an oral agreement with them to supply a product with the quality you need. All regulatory agencies will not believe you because you do not have anything to prove your agreement.

Best Regards,
Fady Khalla