Exactly!!!! There is nothing a Commando/Merc does that another class can't do better. I made this same switch (Mando to Van) and the difference is staggering. The team utility a Vanguard brings vs. a Mando is just ridiculous.
Vanguard: Taunts, Grapple, Stealth scan, 10m Burst Dmg, aoe 3sec stun, 4m interrupt
Commando: 360° aoe Knockback + 5 sec slow, Stealth Scan, Cleanse, Off-Heals, 30m Burst Dmg, 30m interrupt, 8sec/30m mezz, rediculous amount of AOE,
and if specced gunnery: 4 sec Root and 70% slow on Full Auto (which helps your Team when focusing or peeling off)