I'm going to hate that they keep doing this, but the Leafs aren't gifting fringe players rosters spots (last year notwithstanding, when they went with something special). The vets that I don't particularly like on the team are here specifically as hurdles; here the list of bodies that washed up against it and couldn't make the jump:
Holland, Leivo, Griffith
, Soshnikov, Corrado, Marincin, Marchenko, Gauthier
Martin is the main hurdle that has fallen, and they're still waiting for someone to take it from Polak and Bozak and Moore.
The benefit to the coaching staff is two fold. They only have so much bandwidth to handle sheltering and matchups, hence the overwhelming love for Hyman, Brown, Komarov, and the subtle, but very obvious brow furrowing at Bozak and JvR -- vets who were supposed to know what they're doing but for whatever reason can't. So just blowing open roster holes for the sake of asset management means more of their focus would be on sheltering too many prospects. Last season, they sheltered Matthews and Bozak's lines until Matthews started to pull away and excel with a heavier load. Kapanen was injected into the lineup, and away they went.
While I would've preferred having the higher potential options getting time on the lineup, but I can't really argue with results here. The second benefit is when a prospect makes the jump for real, it's really real. Their extended development time shows; they've been tuned for filling gaps in the Leaf's roster (see Kapanen learning PK); they're really invested in proving themselves night in and night out; they already know the System from their time with the Marlies.
