For things that are TOD or beneficiary designation to a person, they can go directly to the named person with only a death certificate. Good, right? The problem is if all sources of cash are set up that way, your estate can't bury you, pay your outstand bills, pay your taxes, etc. No fun to be the executor who has to go around and try to collect money back from inheritors for those things.
Personally, since my spouse is still alive most things are in the trust with only IRAs having direct beneficiaries. Once he dies, I'll likely re-jigger that.
Edited to add: My understanding is that IRA/401k/TSP/etc should not have your trust as a beneficiary bc that means the $$ will be paid out and taxed all at once rather than stretched out. I may not understand the nuances about this issue.