Why did they have those new #1s with Cap and Thor? Because of their respective movies that came out around that time. You can't deny that Marvel characters have had an heightened awareness much more than DC characters over the past ten years.
If it was pure quality that was getting people to buy, then how come highly regarded runs such as Paul Cornell's Action Comics
or Bryan Miller's Batgirl
were not nearly doing as well anything Marvel was publishing. Especially in regards to AC, which is a Superman book. If Superman was that much still in the forefront of the public mindset, shouldn't his related books be rivaling things like Cap, Thor, or Iron Man?
DC has kept most of the same writers and artists for the reboot. Clearly, they were not upset over their employee's work.
I'm not saying other media was the only
reason Marvel was out preforming DC, but it definitely was a major contributing factor in bringing readers back.