###Trendy cosmetics The cosmetics industry grew tenfold after many advancements in biomedical technology, genetics, and general surgical procedures. The trend of self-modification spiraled out of control, and people became effective enough to do most tasks. This technology was then applied to other fields. ###Employment / economic competition After machines became more skillfull and more prevelant than most humans, upsetting the global economy, some scientists took matters into their own hands. So what if you're an abomination when you can compete with the machines and feed your family? ###Biodegradability While the climate changes, plastics and other synthetic products we push out do not. In an effort to create green infrastructure and industry, biological machines became the norm. ###Computation As @CameronLeary said, organic tissue - especially the brain - is incredibly good at small-scale tasks, such as computing. Supercomputers are big, bulky, and expensive, but people can do the job at a lower cost. And so they do. ###No good reason After a cruel, demented dictator took charge of society, they implemented these changes as a way of suppression - and to instill great fear. It worked.

Trendy cosmetics

The cosmetics industry grew tenfold after many advancements in biomedical technology, genetics, and general surgical procedures. The trend of self-modification spiraled out of control, and people became effective enough to do most tasks. This technology was then applied to other fields.

Employment / economic competition

After machines became more skillfull and more prevelant than most humans, upsetting the global economy, some scientists took matters into their own hands. So what if you're an abomination when you can compete with the machines and feed your family?

Biodegradability

While the climate changes, plastics and other synthetic products we push out do not. In an effort to create green infrastructure and industry, biological machines became the norm.

Computation

As @CameronLeary said, organic tissue - especially the brain - is incredibly good at small-scale tasks, such as computing. Supercomputers are big, bulky, and expensive, but people can do the job at a lower cost. And so they do.

No good reason

After a cruel, demented dictator took charge of society, they implemented these changes as a way of suppression - and to instill great fear. It worked.