This is kind of an opinion piece but I think some may agree with me when I say that Tacticals feel off. I do know that they are going to get some love in the first patch but I'd like to discuss this in one thread specifically about Tacticals, their role and their gameplay.
The problem when designing the Space Marine faction is in the idea of a line unit. In Dawn of War 3, a line unit is your bread and butter, your backbone, your primary meatshield even. The problem with this is that Space Marines don't really function in this way, being rare and deployed in situations where a battle needs a quick resolution.
The reason for this is that even the most basic Tactical Marine is a serious force to be reckoned with. From range, they will turn you into a cloud of blood with a well-placed bolter shot. From melee, they will crush your bones with fist, knife or even the butt of their gun. They withstand heavy fire while truly holding the line and not giving it up.
In Dawn of War 2, Tacs were kind of implemented in this way but it worked due to the small scale of the game. It allowed Tacs to be exactly what they should be, an option for every situation. In Dawn of War 3, Tacs have fallen to the wayside a bit - Dire Avengers shields make them a better line-holder, and Orks have an easy time disrupting them with stikk bombs and powerful melee troops. The Tactical has been out-shone in almost every way by its melee counterpart the Assault Marine, which while also very powerful, has become a no-brainer option for most people. It's obvious that the kill-team is what every Space Marine unit would be if the game design wasn't based around line troops.
It's sad to see the Tacticals Marines dying in droves and becoming a fodder unit. Hopefully after a buff they will stand out a little more, but until then it's all about creative play which is somewhat limited by their rank as the line unit.