Cloudformation Import of RDS resources modifying settings

Hi! I'm trying to import a number of existing resources into new Cloudformation stacks. I've been able to successfully import EC2 resources, VPC resources, etc. AFAIK, one of the defining features of a CloudFormation import is that the resources are left unchanged, they're only added to the stack. It pretty much says so in the AWS Console CF Import:

"During this import, you need to provide a template that describes the entire stack, including the target resources. If existing stack resources are modified in the prepared template, the import fails."

The thing is, when I try to import an RDS resource, it requires me to add several parameters, such as DBInstanceClass, AllocationStorage, MasterUsername, MasterPassword, etc. Two things here:

1.I've seen the CF import modify RDS settings such as MultiAZ and, more troublesome, MasterPassword, both from CLI and console.

2.If no modification is done to a resource when importing it, why is it asking for a number of parameters that have already been defined for the resource? I haven't seen EC2 import do it that way; EC2 only asks you for the Instance ID, Deletion Policy and that's it.

Am I doing anything wrong here? What I would like to do is to add those RDS resources without making any changes at all to them, just like I do with EC2.

I know I could add the existing RDS resources to the template with the exact same settings that the resource already has and it shouldn't be a problem, but still, it doesn't look that polished to me, and I'm thinking I may be doing something wrong here.

Thanks!