I agree that it is a bug for official Ubuntu images to subset the standard seeds in a way that deviates from the definition for those images.
I also agree that in this case, installing grub-legacy-ec2 doesn't seem like the correct fix. We should instead fix the seeds to not include grub-legacy-ec2 at all as part of ubuntu-server, and then only install it as part of the image build for those targets which require it.
I think the main reason this change hasn't already been made is that it's not clear which targets still actually require it.
I agree that it is a bug for official Ubuntu images to subset the standard seeds in a way that deviates from the definition for those images.
I also agree that in this case, installing grub-legacy-ec2 doesn't seem like the correct fix. We should instead fix the seeds to not include grub-legacy-ec2 at all as part of ubuntu-server, and then only install it as part of the image build for those targets which require it.
I think the main reason this change hasn't already been made is that it's not clear which targets still actually require it.