That is very true. Berry Gordy was known as a bit of a tyrant when it came to controling his artists persona's; both on and off the stage. But he was also a man with a keen eye for talent and as a producer does, molds the talent into being a very commercialy profitable asset.
But the same can be said for most labels back then. The label had the control and owned the material; even if the artist wrote it. It wasn't until probably the 80's and the 90's before the individual artist really started getting any real control over their product. Zappa talked about the battles he had with WB all the time. Its also the reason MJ owned the copyrights to so many of the Beatles songs. The label controlled everything back then.
But as bass players, I think we can see the impact of the Motown sound and how it affected our roles within a band. Bass was no longer just a background instrument, but really started to shine as the instrument responsible for the groove. I often said, drums make people tap their feet. The vocals and the guitars are what people are actually listening to. But whether they know it or not, its the bass that gets the bodies moving. The Bass is the groove their dancing too. And it was labels like motown that helped make that possible, and it was artist like the Jackson 5 that made motown what it was. Michael Jackson basically just took those same things he was doing under Motowns control and took it to a whole new level.
But even to this day, unless you are doing it yourself or are signed to a smaller indie type label, you will find the label still retains quite a bit of control over the actual music being produced. At least until you reach that level of success where you can tell the label where to go.