There seems to be no consensus on stack traces. Personally I find them very useful, you obviously differ in that opinion but still do see some usefulness, while others think they are simply evil incarnate.

To be honest, I wanted originally to use exception objects, but so many people/tools/programs expect die to throw a string and so many existing exception-object modules jumped through so many hoops it just turned me off from the idea. That said, these days I use Throwable and love it.

If you use one of the standard exception mechanisms, like for example Carp, judicious use of @CARP_NOT can slim down the backtrace tree easily

Moose does use Carp actually.

I will the first to admit (and I suspect many of the other core devs would agree) that Moose could use some better errors. There are few modules out there that couldn't use some help with errors, it is all too common to leave them till the end. Any help you would like to provide, I am sure would be greatly appreciated.