DSP controlled subwoofers can make improvements and like you said do give manufacturers more control but so does using better quality components like the driver itself. The degree of its benefits depends on other components involved in the design though. DSP or lack there of is not a deal maker or breaker for me personally. The overall design is whats important.
When it comes to commercial subwoofers and with the added cost of DSP technology, I wouldn't put it past manufactures to make trade-offs in other areas of the design to hit their market price points. All I am trying to point out is a subwoofer that has DSP technology involved is not necessarily better than a non-dsp controlled sub and vice-versa.
DSP technology does have a lot of marketing appeal with consumers as selling point over other components in the design like the quality of the driver and cabinet which all have an affect on the overall performance.
