JSRs: What Lies Beneath

The example of the complication involved in making Strings in switch statements efficient intrigues me. The point is that implementations are more complicated than they might first seem. But it looks in this case like the additional complication was (in part, at least) a choice.

I don't see why the initial implementation couldn't be simpler. Wouldn't the simple implementation have similar performance to the status quo (i.e. using if statements), with the immediate benefit of cleaner syntax? In fact, why should this level of optimisation be part of the JSR at all? It sounds like something the JVM implementers could optimise without any change to the way the switch works. Tying it to the JSR makes the spec more complicated, delays an initial version and forces this optimisation to be prioritised over others.