Classic movement does not have a skill gap in movement mechanics. Where as H5 movement does. And that's why I like H5s movement.
This is obviously not true since not only strafing obviously a movement skill, but otherwise trick jumping would not have been a thing until Halo 5. And I don't mean this just in a technically-correct-but-irrelevant sort of way nor am I suggesting that turrets and traffic cones are meaningful elements of map design, but that these tricks exemplify elements of timing and creative use of game physics and map geometry that would not exist if the mechanics didn't afford for significant degree of movement skill.
Nothing in classic Halo prevents you from creating map geometry that encourages exploration and skillful chaining of jumps, but at the same time, because of the limited movement range players have, nothing prevents you from creating a map that doesn't demonstrate any of this if you don't even acknowledge the possibility. Bungie never did, which is why we don't see classic Halo as very movement oriented. In contrast, because Halo 5 gives players such a large range of movement—a lot of which is accessible only via button combinations that require dexterity—it's difficult to make a map in the game that doesn't demonstrate the movement skill in the game, the trade-off being that you, as a map designer, have less control over player movement. Not to mention that in designing a new set of movement mechanics, the map designers of Halo 5 were forced to think of the problem of movement and were therefore in a much better position to work with what they had.
I'm not going to claim Halo 5 doesn't have significantly more movement techniques the player can execute than classic Halo, because due to the number of different Spartan Abilities it obviously has. But people tend to place disproportionate emphasis on the importance of movement mechanics vs. map geometry when it comes to designing movement oriented gameplay. I think better results than Halo 5 could be achieved with a more conservative movement mechanic sandbox and better understanding of the mechanics and map design. Unless of course if you place disproportionate importance on the dexterity of pressing as many different buttons in quick succession as possible. In that case you'd rightly think the more mechanics the better.