The major issue that many people have with runecrafting is that it's extremely boring. Whether double nats are good money or not, it's a boring goal from a boring grind.
Most other skills are just as boring tbh. The thing that makes runecrafting different is that, prior to level 77, there is no way to idle through it. It is more click intensive than most skills yet has slower xp rates.
For me personally, even if runecrafting had a rewarding end-goal in terms of profit, I still wouldn't be any more interested in training it to reach that goal if the gameplay loop of the rewarding content was still boring.