Reasons:

1. They refuse to write a will, it's now or never

2. They're tripping over this stuff and getting rescued by the fire department or paramedics on a semiregular basis

3. There are some actually valuable objects, which they cannot mentally differentiate from the junk

4. I don't want to deal with this on top of being sad they're dead, I'd rather do it while I'm still annoyed with them