Lets go back to programming 101 here:
Task Manager on Windows' %usage statistic measures the percentage of time the System Idle Process is not running on a core. The System Idle Process gets run when no other thread can currently be executed. This could be due to a variety of reasons: Cache miss, lock, page fault, or whatnot, but regardless, at that current instant, no thread can run.
What this means, essentially, is that if the %usage statistics for a core never reaches much about 80% or so, the CPU core is getting its work done faster then the OS can hand off threads. In short: You have no CPU bottleneck.
Lets take a simple example here: A checkout counter [think a supermarket checkout here]. Each person at the counter can be considered a thread, and each counter can be considered a core. Now, say you have two counters and two people that need to be bagged. Simple example, but obviously, one person goes to each counter.
Ok, you just expanded, you now have eight checkout counters. Meanwhile, you still only have two people who need to be bagged. Now, its quite possible one of those two people has a MASSIVE amount of groceries, in which case, it makes sense for one of the other counters to help out by splitting the workload in two. Its also quite possible both people have very few groceries, in which case, the time needed to split up the workload will take longer then just using one counter apiece.
Hence the line I take: If the CPU is already getting all its work done, why decrease performance by forcing threads to specific cores?
What people like 8350, noob, and others want is essentially core loading, where each core does about the same amount of work. What they are all forgetting, is that if the cores are already getting their work done, doing this will not only NOT help performance, you will actually LOSE performance due to the overhead. But hey, Task Manager looks pretty.
So the "real" issue here isn't that "games don't scale", the issue is really that "games aren't doing more that uses these extra resources". That's the real problem.