what are advantages of running ETL jobs in aws glue?

The special thing I think is that Glue is full-managed ETL service.

As you're saying, EC2 can do what Glue does.

Glue

• can define a crawler for metadata table definitions
• can load data to and from other AWS services
• can create logs
• can run scheduled jobs, on demand jobs
• is serverless

If we use EC2, we need to take care of everything above and take time.

(If the project is small enough, using EC2 might be enough.)