I had a paid internship that was essentially this and enjoyed it greatly. I wasn't paid particularly well but my workload was a project that I probably took about ten times as long to do as I would today. During the run of the internship I was brought into discussions on design and worked under someone who managed to put up with a flood of questions that I sent at them.

I was hired at the end of my internship and switched over to regular work and grew as an independent employee to handle more serious workloads. My internship was an investment that the company paid into me (and other folks) and by the time I left the company I feel like I more than paid that back.

It's essentially just a probationary period at the start of employment but with much less expectation to retain the employee and less commitment from the potential employee to stay on.

My current company looks at internships as a way to promote working here. We want interns to be successful, learn and enjoy their time. It's a larger investment than hiring off the street but the reward for those who get full time return offers pays for itself ten times over.