Today: Why no Backwards Compatability in PS4
Because there were many reasons, first they picked a new more powerful architecure, one that was easy to make games for (a dramatic change as this would mean games would be cheaper to make for developers) but would ultimately be incompatable with the PS3.
But they could have included a mini-ps3 inside the PS4. If they had done that it would have had a collial effect on the production of the console, the PS4 with a PS3 inside would:
- be $100-$150 more expensive
- be significantly larger, to accomidate new parts inside and the airflow to cool the existing and new parts effectively.
- have a shorter lifespan, with more parts and heat means more things that can go wrong. A small issue with the PS3 inside could bring the whole system down.
Ultimately, the PS4 with backwards compatability would be a worse deal in the long run, especially considering that most research on backwards compatibility says that it is not used that often.