High amount of RNG is mostly a tradition of American tabletop game industry that had been carried to early video game industry. Tabletop games from other places may use less RNG, there is a more deterministic class of tabletop games called Eurogame, for instance. Just because many old-school hardcore RPGs (that have been influenced by American tabletop games such as D&D) use a lot of RNG, doesn't mean there is anything inherently hardcore about it.
I guess you didn't notice while playing that games with RNG can be challenging because things often don't go as planned. While games without RNG are boring as hell because things always go exactly as you plan.
Now, since having a variety of people will cover a broad spectrum of the quality of their planning abilities, it is no surprise that many people completely miss this point.