Well I agree with you on one level, although the example you give of a switch statement lacks some ingredients event handling could deliver such as the ability to have multiple events and not to be tied to expection particular named $_GET variables, for example.
What if you have two important $_GET variables plus a cookie variable you want to response to? You're talking multiple switch statements or if/elses.
I'm not saying I've got a perfect solution (probably far from it) but the idea is by wrapping up your code in a series of handlers, it could become extremely easily to reuse existing classes and handlers.
All in all, it's a result of frustration from having built applications which ended up in giant and unwieldy conditional statements in index.php
It seems that truly useful event registers would have to be implemented by the application server (PHP engine, for instance) rather than wedged in by way of some overbearing PHP classes.
Think you're right perhaps I don't think the PHP group really responds to demand but rather what they've got time for. Some would also argue that the PHP engine should be kept free of such things.
Interesting point though, while you're suggesting application servers - http://sdk.ez.no/sdk/ezutils - the Module Handler for example and the HTTP Object Persistance classes...
Been fooling with ezPublish alot recently, at work and at play - the current version handles events in a fairly crude way (looks for a particular filename then uses switch statements within that file) but is already excellent. You could already describe it as an application server in some senses. Version 3.0 is on the horizon and methinks it's gonna rock!