The trend is in the direction of requiring open code and data. There's been a big movement that direction in economics, and most fields will likely also move that way, so it's more a question of whether you should do it now or in the future.
For the journal I edit, authors are required to include the code and data with the submission. The code and data are available along with the paper if it's published. We do replication audits of some papers to make sure you can take the materials they've included and reproduce every result in the paper. If not, the conditional acceptance changes to rejection. I've had cases where reviewers found errors in the code, so I rejected the paper.
On the argument that it's a competitive advantage: what does that mean? You should be able to claim results but not show where they came from? That's not science.
Keep in mind that this is a "source available" requirement, not an open source requirement. It is a matter of transparency. You have to let others see exactly what you did.
For the journal I edit, authors are required to include the code and data with the submission. The code and data are available along with the paper if it's published. We do replication audits of some papers to make sure you can take the materials they've included and reproduce every result in the paper. If not, the conditional acceptance changes to rejection. I've had cases where reviewers found errors in the code, so I rejected the paper.
On the argument that it's a competitive advantage: what does that mean? You should be able to claim results but not show where they came from? That's not science.
Keep in mind that this is a "source available" requirement, not an open source requirement. It is a matter of transparency. You have to let others see exactly what you did.