[vor_]

That very well may have been a factor. However, Apple engineers have publicly stated that for them to continue supporting PowerPC Macs would have required developing and shipping system APIs targeting a processor they hadn't sold in over half a decade. I think Rosetta's number was up regardless.

[msbarnett]

I think that would only make sense if they wanted to allow people writing new software targeting the PPC to be written, using new APIs.

To support only applications that existed prior to the Intel switch, they wouldn't need to back-port new APIs.