Hi Mark,
A transform could certainly be used to do the same thing. In general we would recommend customers to use a transform for those simple types of operations.
With Connector Customizers, since they are so easy to build and test, I could see a lot of customers opting to use them instead of transforms for even these simple operations, and there isn’t anything inherently wrong to using them in that way.
The advantage to using a transform is that it can be used on all connector types (VA as well as SaaS Connectors), and you can also apply multiple Transforms to a single connector, while only one customizer can be applied to a connector at a time.