"Besides, most customers don't want really accurate speakers anyway and wouldn't know one if it hit them over the head"

Skeptic! we agree on this point (Your tally will be updated to reflect this)
The JBL "Signature Sound" was in place long before I got there, and will be there for many years to come. It just gets spiced up or toned down depending on the target audience.

"he can give them a story about breaking them in or switching to vinyl or buying a tube amplifier "

Vinyl and tubes aren't for everybody. I like them, but I'm not into the "old tube" sound, nor the "old vinyl" sound which is what you describe. Things have changed out there.

"or special cables to roll off the high end"

Skeptic, you have just stepped into the "doo-doo". You have now admitted to coming over to my side of the cable debate. It IS possible to build cables to tune a system, there can be differences, and often those differences are destructive in nature. Don't you feel better now? (Your tally will be updated to reflect this)