Past experience plays a huge role here.

If you never experienced role playing games, the learning curve will be steep. You either will like them in the end or not, but once you had some experience with them, as many people in this thread pointed out you are open to the world of assumptions, shortcuts ect.

Paul Beakley as to the boardgames and rules in them.

First rules in boradgames are way shorter than your average RPGs. Usually quite easy to assimilate and after a game or two you know how the game works, got basic strategy down and know the goals. We all know how long does it take to figure out currency mechanics to a well developed game, essential step for system mastery and “getting full experience form the play” (not for everyone but for rather big chunk of the fans).

Second RPGs are notoriously bad (getting better as time progresses!) at explaining rules and even more broader concepts – playing the game and roles at the table. ect. That creates a lot of assumptions and pointless discussions, trying to figure out what author said. That is to your point about BW boards, people just assume that rules are full of holes, and they have easy fixes for problems that do not exist in one game, but they encountered them in the other games they have played in the past.

Third thing – time commitment. I think this is a main factor in why people are hacking the games to their liking, and do not want to play by the rules. If you are aware how much time the average game will take, you are less likely to even approach a game with an open mind – 6 session for beginning to comprehend what is going on systeme wise? Way too long for some. Boardgames have rather clearly specified time frames for a round of play. In RPGs everything depends on people involved.

Fourth. Social aspect and table dynamics. A whole different can of worms as there are infinite variables. But I saw that people who game with a lot of strangers, or are in multiple games with different people better handle new system exploration and are more willing to try something new.