I think this is part of a bigger systemic problem with RPGs that started out small but also made for a great study in how the Skinner-box can be applied accedentally.
As people have already stated, there is an optimal way of playing through the games -- looking at the cost/benefit graph. For the cost of some minor inconvinience for the player (not the PC) you can gain a huge benefit for the player character.
We also know that most players don't play through a game more than one time. I would venture a guess that most people who are planning to make the odd characters tends to wait for a second playthrough and have the first playthrough be a normal one.
If we were to put these two together you will end up with people going for an optimal playthrough first before playing a concept character -- like an all out social one with no combat skills.
I want to be clear and state that I do not have any statistics to back this up, but im sure Obsidian would know more from what telematry they collect from the games. I am also sure that some people will just follow the story path and not stray form that path cause in the end that's what they are there for. Basically what I am saying is that without getting a look at the data i can never be sure how previvalent any specific gameplay style is. Though I would guess that the standard path and the optimal path are the two most previvalent paths taken.
Anectodally i can even say that those i know that play a style far removed from min-maxing tend to be bitten by both LGD (Looting Gathering Disorder) as well the DED (Dungeon Exploration Disorder). We have all been told that money is good to have and most games have some really expensive stuff you can buy that will give you a nice edge. So why not try and get that edge if you know it will have no penalties? Who knows, maybe that dagger you picked up can be the difference between getting that item you want or having to wait for another 4-5 hours to get the cash to do it -- by which time it is already undesireable as you are now higher level and have found another shiny you want instead.
DED as I jokingly call it is even worse. We have been shown by the developers that every dungeon has some secret treasure and it is normally a really attractive one for the level we are currently at. This has trained us into scavanging ever corner of the dungeon just to make sure we dont miss out on that sweet treasure -- or even worse, every path of a maze.
And even those who I know to be more layed back in their gaming suffer from both LGD and DED. Maybe to a more minor degree than I do -- being more of a powergamer myself I suffer from both of these to a higher degree than my more layed back friends.
There are also more benifitial sides to this than mearly the monitary one. To get said loot you have to kill things to loot and grinding for xp and gold tends to also give you advantages in how you are allowed to roleplay your character in the system as you tend to level faster and get more points to spend -- which trantlates to more options of how to play depending on how you spend them.
I mentioned the Skinner-box earlier in the post because it's how I personally see that this problem has evolved. We did something and got rewared for it to the point that we dont really think about why we are doing it now it's just what you do. Isn't it normal to go through every section of a maze to maybe find a strange chest with a broken glass vase it it? Isn't that how the real world works?
Personally i think that this is something that needs to change, not nessecarally go away, just change. As games evolve and game designers get more examples to look at they can see better what works and what didnt work -- not to mention things that worked but not as intended. If you give the characters an infinite inventory and have no limits to the gold on merchants you might just be making loot hording easier instead of looking at why loot hording happens and if its a good thing.
Now personally i tend to agree that any mechanic that you can easally workaround is a bad one as all it adds is anoyance. Is the merchant out of gold but will restock in 2 days? I guess its time for me to rest for 2 days -- it's not like 2 days mean anything ingame anyway, there never seems to be any time limit on anything. In these situations the mechanic simply adds anoyance without adding any enjoyment to the game. But perhapps the problem isn't that the merchants are out of gold, maybe its the fact that we are selling so many items that's the problem. Maybe the reward of having a lot of gold should be looked over as well?
Anywho I fear i am not rambeling so i shall stop before i start going in circles.
Hopefully some of what I have typed out will make sense and be some food for thought in the overlying discussion.
-TSD