4. No expensive items.
5. No titles or tasks (daily/monthly/otherwise).
If obsidian armor didn't exist, I know that a lot of people wouldn't have spent as much time farming. They just wouldn't have ended up playing as much. I am talking about optional grind here of course, many people will give it a pass because it doesn't give any benefit that you have that armor. It still causes people to grind though, and it gives players that don't have as much time to play as they want, an excuse to partake in cheating, scamming or even in rmt.
That's not to say that economies with expensive non-game changing items are flawed, just that there are people who have problems because they'll play a game that they do not enjoy, or even loath... if it has a task they feel they must do for whatever reason. There was this one person in my alliance once that cursed out anet every chance they got because of... I think it was one of the vanquishing titles? They'd tell everyone that they were going to get gwamm before they stopped playing "this horrible game", but that anet was evil because they designed the titles to be too grindy. It didn't matter to them that it was optional grind, don't ask me why. I mean, I think I know why, but I'd rather not talk more about that particular person. Like I said, some people have problems.
What it comes down to for me is this: Is it possible to complete hearts without doing one or more of the actions that is requested? Not because that would keep it from being grindy, but it would make at least one of the actions as an optional grind. I didn't play enough to feel comfortable answering this one way or the other myself.
At least pvp players don't have to worry about pve grind, and pvers don't have to worry about pvp grind. Though from my time in warhammer online, I'm aware that there will be issues, at least at first, with people who will grind pve when all they really want to do is go play some WvW. At minimum they'll grind their weapon skills so they aren't reduced to spamming "1" against players who have a full skill bar, but somethings telling me some will avoid WvW completely until they've hit level 30, because they'll want to be able to have an elite available when their opponent uses theirs. And well, max level armor will keep a few people out of WvW on anything but their best equipped characters.