Well, in fact, Intel and all the other major makers spend a huge amount of effort benchmarking important workloads. It isn't a decision to optimize for Unix or Windows, it is a decision to chase dollars. They will optimize processors for your favorite workload, too. Just demonstrate how many millions of dollars of business your workload represents, and create some sound benchmarks for it. Easy.

Any information on how many millions before a workload becomes interesting to Intel/AMD/Nvidia?

Well it's certainly better than what they were doing before, trying to look like the iAPX 432 with their memory segments and all that stuff.