Even more interesting things to mule over while the servers are down.

[SpiritMuse]

Q: When I delete a person from my friends list, I want my character to disappear from theirs, as well!

Yoshida: That would lead to the problem of “Why did he delete me?” and might cause trouble, so we didn’t do that on purpose.

Honestly I'd take the "Why did you delete me" awkwardness over a former friend still retaining access to our every location and the potential for harassment, depending on how the friendship ended.

[Solarra]

Honestly I'd take the "Why did you delete me" awkwardness over a former friend still retaining access to our every location and the potential for harassment, depending on how the friendship ended.

^ This!
The 'trouble' that might be caused by someone finding you've deleted them from your Friends List is trivial compared to the potential for someone to be stalked and harassed by former friend who they want no further contact with.
Yoshi has given this answer before and I have to say his logic baffles me. He's blowing a little social awkwardness way out of proportion while ignoring the very real problems that can occur when someone with malicious intent has the means to track another player in-game.