Because they are much cheaper than bass 12k.
The context of this thread is user is looking at DSP amps over bass line.. I wouldnt use DSP amps for bass but then again.. I wouldnt use the bass 12k on that 1 sub either unless plan on adding more subs in the future.
The new HD8000s to HD15000 are good for bass now but we have already publicly stated that once the bass models start to come in that are equal in rated output to the HD line, we will drop those HD models from stock.
We can still sell any amplifier even if we do not stock it, it will just take an extra 3-5 days to special order them before we ship back out.
About 90% of all customers and dealers that have moved amps this year over 10kw from Taramps have chose hd15000 over bass12k because of price mainly and have been satisfied.
Those who are running the bass 12ks typically are running well under 1ohm and are satisfied. They feel more comfortable abusing the bass line over the HD line.