Metro, I'm still struggling to see your complaints about exploration. Let me try to illustrate how I find exploration still entertaining:
This map shows only major quest participants in the cities and only shows quest related caves and encounters with a few odd exceptions. It's not complete, though there's apparently a Gothic 3 Interactive map that's more complete, if anybody's interested. Similar maps to the above are available
here.
I'd estimate very roughly that this map covers an area you can traverse inside of ten minutes at walking speed, to give some sense of scale.
In it, you can see four quest related mines to interact with (clear out, explore for loot, support by completing a quest), one bandit camp (Ivan) to clear out (also a quest of sorts), five quest relevant monster encounters (and dozens more that are not shown, including a golem, special monsters that you need to kill to harvest their poison glands, and a valley full of shadow beasts, to name a few), at least four 'hidden' quest participants (Runak, Bollock, the slaves and Maxin) that you need to find, two major ruin sites with loot, a secret rebel base (also important to discover to properly complete a quest), and, my favourite, a dragon on a hill that you can only access if you're the kind of game-breaking 'tard that tries to jump glitch over a mountain that looks like it should be an invisible wall.
Leaving aside the question of loot for a minute, there's a lot of stuff here that you
need to find to complete or even initiate quests, most of those quests necessary to advance in the game's main plot. There are a lot of unique encounters that you only see if you explore. Without giving away even more spoilers, one of the 'hidden' people is necessary for learning one of the most powerful skills in the game, so
that's a reward for exploration (and he is actually quite tricky to get to). Another quest giver, not hidden but off the beaten path, is necessary to find in order to access and create the best/second best (depends on the context) arrow type in the game, which is another important reward. In short, leaving aside entirely the question of loot, there are hard encounters, character advancement opportunities and quest objectives necessary to advance in the game out in the world. And they're densely packed.
The real issue, in my opinion, with the loot system is that it's not tied to challenge--the relative difficulty of finding a chest and dispatching nemeses along the way. But you talk as if all incentive to explore is removed. I don't see that. Instead, its crime seems to be that you have to explore every fuckin' nook and cranny if you want the best stuff. It seems like incentive to explore thoroughly is increased immensely. The only people punished by this system are people abusing metagame knowledge to try to go directly for the best equipment and skip all that exploration. I think their decision, while kind of obnoxious in its insistence on completionism, promotes exploration rather than undermining it. To draw a contrast, in Risen, I accidentally found the second best sword in the game about five hours in, during the first chapter.
Nothing I found after that was even remotely interesting--the only better equipment was locked away from me at that point--and I just eventually lost my lust for exploration. The Gothic 3 system at least tries to deal with that effect.
It's certainly less optimal than properly designing the difficulty level to make it so that you acquire hand-placed and challenge appropriate loot in a natural progression. Risen only has some ghouls guarding the sword I mentioned, IIRC. Moving away from the dense design shown above and towards a map with clearer danger zones, with opponents that could cream a low level character, would allow them to hand-place loot, appropriate for challenge level. But then again, it's already been accused of being a singleplayer MMO enough, hasn't it? I think that a move in that direction would hurt exploration.
I fully acknowledge that this is an example from Myrtana and in the past you're complained more about Varant and Nordmar's relative emptiness. Who knows? Maybe I'll burn out. But that's more or less how every PB game has been for me so far--the first 50% is heaven and the last 50% is what separates me from the satisfaction of completing the bastard. Gothic 3 changed some things about the formula, but it wasn't random or purposeless, and it isn't a mere hiking simulator.