all Bitcoin ASIC companies had to derive their works from existing the current SHA-2 ASICs, starting from scratch would have cost far more than the Bitcoin economy could have supplied, and far more than ASIC companies could afford to spend at their current price points. Its like if current ASIC companies decided to start using 14nm chips. It would be unimaginably expensive to create a technology that doesn't exist yet, its far cheaper to modify existing designs.
Starting from scratch is equally expensive, FYI your analogy is totally wrong. They didnt create or modify any 'technology' for the their asics, its matter of coding and tools.
next time try using google first before "I'd say its a pretty strong gut feeling."
even reading simple wiki article helps,
http://en.wikipedia.org/wiki/Application-specific_integrated_circuit