Are the Baldur's Gate games worth playing for those who hate the DnD system?
I've played a lot of Planescape which I'm enjoying despite the DnD system, but I gather that these games focus more on the system and the world surrounding DnD.

Are the stories of these games worth putting up with the game-play for those who dislike DnD and generally have little interest in the lore surrounding it?

lol, no.

It's personal preference on what you are hoping for from the story really but but considering you aren't interested in the lore and generally dislike DnD, I wouldn't bother. I do like the Baldur's Gate series but that's because of the gameplay (which you mentioned not liking).

The main story in BG is, simply put, crap. It doesn't even come close to PS:T. The story in both BG games is a mediocre "save the realms from the one dimensional big bad", the lowest common demonimator story you can expect from a DnD game. However, there are some interesting character developments in BG2 but I'm not sure it that's something you'll be interested in. You emphasised story in your first post so I'm assuming your only interested in the main story line. If that's the case, and you don't like the DnD system and your not interested in the lore, just skip BG, theres nothing in there to hold your interest..

Would you go to a football match if you hated football? Surely you can answer that for yourself?

Most people seem to rate them as good games, I was interested in hearing whether there was much to these games beyond DnD.

The games are based on D&D. The fact that you are enjoying PS:T must tell you something. It tells me that it's not D&D that you hate, but maybe some element of it. I have a problem with people (not personal) who require the assent of others before they decide if they like a game or not. Because games are like art (either you like it, or you don't), there is only ONE way to decide if you like a game, and that's to dismiss anybody else's view entirely, and taste it for yourself. To do otherwise places a person in the category of sheep.

In your case, more than likely the answer will be no.

People have a tendancy to compare PS:T, BG and IWD because they are all infinity engine games but those 3 are still quite different in terms of game play.

In PS:T, the DnD system never interfered with the gameplay. The Nameless One had a lot of leeway for character creation and you could still make it all the way through the game even with a less than optimal character, not liking or understanding the DnD system didn't interfere with your game like it would have in BG or IWD. However, as I said before, because they're both IE games, people tend to compare them which isn't a good idea. I'm assuming your logic is this. "PS:T is an IE DnD game and I liked it even though I don't like the DnD system, maybe it's the same with BG?" If so, this is why I didn't see your question as outlandish.

But I'll tell you right now, that's not the way it is in BG. A quick google search and you'll find there are people who couldn't get into BG but still enjoyed PS:T. Seriously, just give BG a wide berth and consider your question answered, or if you have a friend who has a copy, try it out yourself before deciding to plunkdown a few moni coins for them..

Baldure's Gate series is an open-style sandbox adventure, where you can kind of wander off anywhere you want and get killed for your curiosity. It is "epic" in the sense that you eventually level up your character to almost god-like power, and explore through some pretty tough dungeons. It is a quintessential "overland adventure", and gets extra points for the high-quality production (for its age it is still a GoG). But if you don't like DnD, why bother?

Is it really an open-world sandbox when your companions attack you for not going certain places at certain times?
Is it really a good game when the designers specifically chose to create narrow hallways even though they knew the ai had pathing problems in narrow hallways?

Is GOG a consumer-friendly company even though it sometimes messes up and tries to introduce regional pricing? :P

Yes, BG1 really is an open-world sandbox, in which occasionally people expect you to do tasks important to them within a reasonable timeframe.
Yes, it really is a good game, despite some technical issues like the pathfinding and map design associated with that.

Only Minsc, who is mentally... challenged, will actually attack you. Others will leave, but no others will attack for not going along with their personal quests -- they may fight each other over other issues, but not your character. Regardless of that fact, that does not negate the game being open-world or sandbox. And this is exclusive to Baldur's Gate, is it? Of course it isn't. Pathing is a huge issue in many games, even games like Neverwinter Nights which do not use the IE engine.

Yes.

If you have to be at a certain place at a certain time then it is not a sandbox. If areas are conditionally locked then it is not open-world, no matter how often you shift the goal posts. That's nice, but how does this support your stance that Baldur's Gate is good?

Then that's also the answer to your second question, for much the same reasons :)

As for your first, wikipedia describes an open world game as "a type of video game level design where a player can roam freely through a virtual world and is given considerable freedom in choosing how or when to approach objectives." I think it's fair to say that you have "considerable" freedom in choosing when to approach objectives. You also have freedom in choosing how to approach the objectives: feel free to deal with the Minsc issue by kicking him out of the party/killing him, for instance. I grant you that it doesn't satisfy wikipedia's definition of "Sandbox", but then...very few games do, and even Minecraft is pushing the boundaries. Certainly no RPG would work very well if the game let you simply delete the enemies, which would be a requirement for a "sandbox" game by Wikipedia's definition.

http://en.wikipedia.org/wiki/Open_world

If you put it that way then I highly doubt you will enjoy.

Don't get fooled by the overhype of story. If you don't enjoy the gameplay then no matter how good the quality of the story, you will no enjoy the game.

As for the BG games in particular, they have good stories for a game. They are not literary masterpieces and they will not hold your interest if the massive amount of combat you will face is not your thing.

You just don't get it, do you? You do not have to 'be at a certain place at a certain time'. You have a choice: go where you will, do what you want. You are tied to nothing and nobody. And there is not a single game anywhere on the planet, (that has anything approching a plot), where every single area is available from game start. That's not moving the goal posts, that's game design. What? Are you serious? Baldur's Gate is good because *I* think it is good. I really don't care what you or anybody else thinks. No, really, I don't.