The thing behind this is that if you jump to a wall then hit SMART you'll vault faster than just holding down SMART.
That's still more than enough to make the system more... learn-able? Skill-based~ish? Basically, new players can just W+sprint, while experienced players can use manual input, the former benefitting from a more reliable way of movement (like when under stress, when you try escaping from someone and are bound to failing the timing on your actions), while the latter offers a more risky, but swifter way of movement.