In the past DOA had fewer, shorter, and weaker strings. The evolution of DOA gave rise to more, longer, and "stronger" strings to make for more interesting matches and funner gameplay. It's about making the best of your fighter's tools to come away with the W, most people who bought DOA5 find that very fun.
Yes. Tekken also boosts the strings in its evolution. SC seems to be the only franchise that lets the nerf bat fly free. And even today, many SC players still think SC2 was the best, because the nerf bat started to hit hard in SC3.
Nerfing Strings and the move list in general is extremely unpopular. And I think SC Devs are very aware of it. Still, they do it. And I think they do it because they know that in the end, it's going to increase the overall complexity... as counterintuitive as this may sound.
I can't tell that they nerfed holds as I main Lisa and I can generally deal as much damage as take (or more) when them when I use them out of stun, her hold rating is 4/5 so that may have something to do with it (it seems like a 5/5 to me).
I guess it has to do with her hold rating. But I'm also comparing DOA5 to DOA2U. I don't know how the Holds were in DOA4, I just know they are weaker/harder than in DOA2U. The specific Hold for Mid Kicks was a considerable Nerf, I think.
Don't take this the wrong way but it seems that you are heavily biased toward SC at DOA. I could take you more seriously if you compared DOA to Tekken hence SC uses weapons and Tekken doesn't. You're basically saying that DOA5 is good, but it's not SC. DOA5 isn't even trying to be SC.
I think DOA steamrolls Tekken. I think Tekken looks horrible! And it also lacks a decent combo mechanic, so it 'overuses' launchers and juggling (which look the worst among fighting games) and pretty much every combo looks the same, besides being ugly.
I agree that the weapons are an important aspect that differentiates DOA from SC. Because of the (lack of) weapons, I wouldn't expect DOA to have strings as weak as SC's, neither range as complex as in SC. But it could still have weaker strings and more complex spacing than it currently has.
I don't actually expect these changes to happen, though. Even if utopicaly they did, they wouldn't be a patch thing; but a new installment(s) thing.