Vanguards and Powertechs aren't useless because of 1.4, notice all the ranked teams and players still dominating with them. If you actually read into it right, they actually got a damage buff with Sticky Grenade/Explosive Dart now on a separate CD from Assault Plastique/Thermal Detonator. Just learn how to kite the marauders and keep them in the 5-10m range from you.