Engineering any system is all about maintaining control within specified functional, performance and quality constraints. The use of a DSP permits the physical system consisting of driver and cabinet to be operated as close to its physical limits as possible, throughout its frequency range, with minimal losses in functionality, performance and quality. Hence excellent control. Now that doesn't necessarily mean that you can't find a non-DSP sub that sounds better than any DSP sub. But, can you find a non-DSP sub that does as well with movies as music in large and small venues? If you do, let us know.
