I hear you, but for everybody who wants to export filters, there's somebody who wants to export just something else (address book, messages, settings, etc.). There really is no end to it, and it's a PITA to cover all those cases. I'm pretty sure that's what plugins are for: if there's enough demand for a filter exporter, somebody could write a plugin.

Most people just want to export everything (e.g. to transfer their acct to another computer), and for that they can use the build-in full export (Tools -> Export).