You remember when RPGs used to give you random amounts of stats when you leveled up? That was stupid, most RPGs have removed that random element because there was nothing particularly fun about saving before you leveled up and reloading until you got a "good" stat level up.
You ever hear Yoshi talk about why the bosses tend to do more scripted moves than random ones? It's because he wanted the players to win or lose fights based primarily on their skill. If the fights were too random, you'd end up with easier or harder versions of the fights depending on which skills got used and in which order. So a player might win a fight once because it did the moves in an "easy" sequence and then lose a fight because they got a "hard" sequence. Players do not want to lose fights "just because", they want them to feel fair and that they lost them because they made a mistake. So, while there are some random elements to the fights, most of it is pretty scripted so you get a reasonably consistent experience from one attempt to the next.
Advancement and gear is also important to RPGs. People may kill stuff a few times just because it's fun, but you'll need to have that carrot on this stick (loot) to get them to keep killing it. This way content doesn't get outdated too quickly. By the same token I think having massive RNG is a lazy way to set up the carrot and the stick. When you base advancement (loot) on RNG, and then make that RNG very low, then by the same token, a player's ability to progress is going to vary wildly depending on how RNG treats them. Some RNG is good so that people don't necessarily know exactly what to expect each time. However, too much and you're going to end up with too many players that chase that carrot, never get the stick, and are going to be put off by the process. Which is why I feel it's bad, and really lazy.