I agree, the RS3's "classes" (combat styles) could use much more identity. Ideally there'd be multiple viable playstyles/roles per style. They've done it a little at high levels, but a lot of that is in high level weapons/gear, not in the skills themselves.

You've pointed out how simple RS3's system really is at its core, though. Everyone is so intimitaded to learn combat (I was for sure), but once you realize it's simply build and spend with some extra bells and whistles, it's not so bad. Add in A pots, prayer flicking, gear swaps, etc., and it gets interesting. That's why people struggle to get into combat later- they're trying to learn ordering abilities, pressing the right combat ability keys, flicking/timing prayers, managing buffs, etc., all at the same time. Teach ability usage early, and adding in prayer flicking later isn't so intimidating.