I'm not sure I understand what the advantages for the losing team are.
So let me see if I understand this correctly, the supposed advantages are:
1. Decreased respawn timers.
2. Gold advantage.
3. Easier quests / easier to assault points
Am I misunderstanding this? If not, it's easy to see where most of those are either not advantages or to be expected.
2. Gold - This one I completely don't understand. If you die, you do continue to gain gold, however, how is this any different than SR? If you're dead, you can't kill minions or capture points or get kills/assists, which are all three alternative sources of gold. So...I really don't see how this one is any different than SR.
3. Easier quests / easier to assault points - This makes absolute sense. Remember, this is a game of territory control, not a fortress assault. SR's fundamental game play is that once an objective is completed, it's not reversible, that is to say, you can never rebuild turrets (although inhibitors respawn which mucks it up a little). Dominion is completely different, it's more like Risk in that sense. Each gain you make can be undone by your opponent. And in that sense, that makes complete sense. In Risk, if you tried to control all of Asia, you gained a massive boost but it was darn near undefenseable because of how thin you had to spread yourself to do that. Same thing in Dominion, if you extend your territory that wide, then naturally a concentrated assault force can overwhelm a thinly defended turret.
The quests are easier? Again, that's only natural. The quests are for seizing territory. If you've already seized the majority of the territory, the only thing left for you to take would be their stronghold where their defenses can easily be concentrated. On the other hand, you're already spread thin, so of course they can easily assault your tower to take the quest.
EDIT to add another point: Remember that if you're up say 4 turrets to 1, the quest will become fair easier for them for one simple reason....they have almost nothing to lose. The difference between 3 to 2 and 4 to 1 is massive, it's a 300% increase in difference. So let's say they ball up and assault the quest point with 5 people, at worst case trade off it's a 4 to 1 shift to 4 to 1 shift, they take the point and lose the other point. If you're up 4 to 1 and assault that one point...you have 4 points they can assault while you're taking the quest. You have far more to lose and those have to be more hesitant in resource committal.
The only thing left is the respawn timers. I will be honest though, the explanation given doesn't make much sense. True it does somewhat simulate being deep in enemy territory on SR and dying and how that would reflect in how long it takes to get back to the action. However it completely disregards the fact that in SR if you die two feet from your nexus...you still have a very long respawn timer in which the enemy can press a large advantage. I see where you're going with it, getting back in the action is really respawn + travel time (hence why TP is so nice) and just respawn time, but I think the fundamental flaw is that thinking that since travel time is lessened that you should increase respawn time, the two have fundamentally different aspects to them in how they affect the game flow and as such can't be considered interchangeable.
P.S. I'm for Dominion, I love the gameplay and have had several wins where I was 400+. I've had some loses that way too. The key is never let up.