While it's important that Yotsuyu's story is told and learned from and not forgotten, making a grave (or more likely a memorial) to her in the city would be the wrong approach. In time the people might be ready to hear it and regard her with pity, but for now it would be a reminder of those still-raw memories of suffering - every bit as much as the watchtower they've chosen to tear down.
And talking of memorials....
Haurchefant's memorial actually isn't a grave either, at least as we'd define it - his body isn't buried there. (It's not pointed out, but Corentiaux at Camp Dragonhead mentions it if you talk to him.) Which seemed an odd thing, particularly as the pre-existing stone cairns are referred to as a graveyard in one of the dragoon quests, but the question got brought up in a Korean Q&A a few weeks back and the answer is rather lovely.
Discussion thread:
http://forum.square-enix.com/ffxiv/t...A-with-Yoshida
Document link:
https://docs.google.com/document/d/1...ClxamIIE64ca0/
So (unless the lore team have a different answer), graves are not necessarily physical but "where the person would want to be".
Which I suppose comes back to the question of Yotsuyu - would she even
want to be in Doma?