How dare you sir!?
Seriously though, I think the new rules for Seraphim are sweet. And rumors will say they are 14 points, making them incredibly cheap for 3+ save jump packers. The problem is, Dominions with Scouts are
exactly what the army needs. The one thing that SoB truly need is long range anti-tank, or failing that, a surefire way to get meltaguns into the enemy's back field. Dominions provide that because Scout moves always work, they always get to move halfway across no-man's land before the game even starts.
Seraphim don't provide that. If they deep strike, it's very risky, especially if you want them to land close enough to fire their melta pistols on the turn they arrive. Plus, if you deep strike them, by the time they actually arrive they may be too late to salvage the game.
Xelloss makes a very excellent point, that with 3x units of Dominions you can achieve local superiority. You don't run the Dominions right into the enemy's teeth, you strike a flank or an isolated part of his army. This forces the enemy to either absorb the harassment, to his detriment, or divert forces to go after the dominions, keeping pressure off your main force. Either way, it solves SoB's principle problem: that for the first turn, you ordinarily do almost no damage to the enemy and just get pounded by his ranged fire. The first turn of eating lascannons and missile launchers with only Exorcists for retaliation can end the game if the enemy's anti-tank rolls well. Dominions have the potential to negate that because of how they can force the enemy to divert his attention or contribute significantly to an alpha strike.
Bubble wrap is a bigger problem for Dominions, but it's more of a problem for Seraphim. Dominions can tank shock through bubble wrap, potentially forcing it to flee. You might also be able to tank shock the edge of a bubble wrap unit, knocking enough inches off its radius to hit the protected tanks with your meltas. Seraphim, on the other hand, can't do anything but assault the bubble wrap--their melta range is so short they can't expect to bypass it in any way. Assaulting the bubble wrap is a good thing if your goal is to get rid of it, but your true goal is to hit the tanks it protects. Plus, deep striking phim can't show up until turn 2, and can't assault until turn 3... If the bubble wrap is still there on turn 3, it's done its job and may well have won the game for your opponent.
As for outflanking Dominions, the only time I'd consider it would be Dawn of War, where normal scout moves aren't possible. In that case, since you can't make your normal scout move, you're not really losing anything by outflanking, though you're still taking a risk that an important part of your army doesn't join the fight until too late (or it joins on the wrong side). The same reasons why deep striking Seraphim doesn't work apply to outflanking Dominions. But even that tactic beats deep striking Seraphim, because at least there aren't any mishaps.