That would depend entirely on the player. Lots of people love Planescape: Torment because they like the story despite the fact that the game itself is terribly designed. On a similar note, as you might guess, I love Morrowind because of its fantastic atmosphere and setting despite the fact that, again, it's not a very well designed or difficult game. But that's hardly universally true. Given that video game writing is, on the whole, rather terrible, I have to assume that most players are not like this, however.
Pillars has a decent story but I enjoy the problem solving aspects of the higher difficulties and for me that's what puts it above many other RPGs. This difficulty is much more than simply memorizing a formula unless you go out of your way to seek out overpowered cookie cutter builds on the internet, in which case you have only yourself to blame.
EDIT: Also I hate this segregation of gameplay and story in games and only use that language myself because everyone else is so dedicated to it. A story is meant to evoke emotions and gameplay can aid in that by making a desperate fight actually feel desperate. But story driven games often neglect this to their detriment, with things that are supposed to be threatening simply seeming pathetic due to the ease of their defeat; all playing in to the plague of overpowered Mary Sue style player characters in modern RPGs.