Being a massive fan of the lore behind W40k I actually welcome the smaller scale employed in DoW2. It's much more in tune with what you always read in the novels: The Space Marines are humanity's last defense against innumerable hordes of enemies, extremely powerful but very few in numbers.
Also, if you want to get the most out of your squads and their abilities, especially on the more difficult game modes, you do have to use advanced tactics, otherwise you'll get ground into paste. It's simple enough in the first few missions, but later on the story gets a bit more interesting, the big story missions (such as the battle at Angel Forge) are pretty epic in scale, and some of the bosses are difficult to overcome, such as the Ork Waaaaaghboss or the Avatar of Khaine.
Oh yeah, and you'll get one more sargeant later on who kicks so much ass it's unreal.
EDIT: If things got a tad repetitive for you in the DoW2 campaign, check out the expansion pack Chaos Rising. They got rid of the grind aspect and added a well-designed Corruption mechanic to the gameplay which greatly influences both a big plot twist in the second half and the ending you'll get based on the seemingly tiniest of choices you make along the way.