I think DOW2 successfully replaced basebuilding and focused on tactical elements, and that it ended up a better game than it would have if the reverse were true.
It's funny you mention DoW 2.
Because Company of Heroes, made two years before Dawn of War 2, by the same company, pretty much perfected base-building in an RTS in my opinion. You had your standard base blah-blah-blah, but then a lot of defenses with no real limit on them to really entrench yourself. Being able to build cover and pathing obstructions, and have it all work, pretty much makes Company of Heroes the best RTS I've ever played, far and away more interesting from the defensive side than stuff like SC and its ilk.
And then they went and made DoW 2, and I couldn't have been less thrilled. At first I was like "Omg, new engine, Company of Hero details, and 40k! I'm in heaven!" But then I saw they basically threw away most of the innovations they'd come up with in the last few years.
Putting the entire focus on troop movement and tactics demands that they're really deep enough to satisfy. But in DoW 2's case, it was the same basic squad setup all Relic fans are familiar with, combined with uber powerful hero characters ala Defense of the Ancients. The "tactics" therefore, revolve around dealing with the OPness of the heroes in comparison to your squishy (but completely necessary) troops while not getting flattened by the hero's support troops. Cue the kiting, Assault Squads, stuff with an AoE or knockback, long range weaponry, and of course, walkers.
It's a fun, spammy little mess...until the fight is over. Then there's nothing to do but go capture the next point, do some very minimal upgrades, and prepare to die some more.
In the end, that's why I don't like the ethos of removing base building, at least in DoW 2's case. DoW 2 games are static. They don't really change except based on player. In CoH, especially against the AI, the game could be drastically different just depending on if you chose to blow out a wall somewhere, or how you arranged your choke points (that's right, choke points YOU create, not that the map either has, or doesn't have.)
In a non-zerg game of Company of Heroes, the act of securing the map and your base slowed the game down...but it made for FUN when you or your enemy slowly rolled back the other's defenses. The pacing felt right.
In DoW 2, it's one engagement of small numbers of troops after another, or guys creeping in behind your base. There's less sense of escalation. If you really hurt someone early on in the game, it can be hard for them to come back from it. And there's rarely a grand, finale moment like assaulting a well defended base. The opposition just sort of trickles down to nothing while your guys shoot one super huge structure.
Or maybe they just skip the foreplay entirely, zerg your drop site the minute they get a half decent unit, and pretty much end the game right there. The pacing is frantic,, the combat is frantic...and I was just sort of left feeling hollow when games ended. When a game of CoH ends, I feel like I just had a feast, and the after dinner mint is going around looking at how FUCKED UP the battlefield is. DoW 2 barely managed to capture that sense of immersion. For all the DX10 shininess the Essence 2.0 engine delivers, it pretty much cut the physics and environmental detail down by half. Which were the best part of Relic games.
I would have enjoyed DoW 2 had I been prepared for how much like Defense of the Ancients it was going to be. I wasn't though. No one was. Even when they said base-building was out, we had no idea it was going to be quite like that.
As a result, I haven't been able to bring myself to even buy Chaos Rising. I should, being a 40k fan and all. I just can't bring myself to spend the money though.
To this day, I wonder what 40k would be like when done to Company of Heroes exacting standards. Sadly, I don't think I'll ever get to know, because Relic is convinced they've pioneered something better....which I'm obviously not in agreement with. And don't even get me started on the campaign. I couldn't believe how repetitive it was.