Zoro's motivations are already good as they are now I agree but I'd say that his actual flashback (the one he got still in East Blue) is pretty laughable. I'm in for Oda actually exploring more of that instead of "ooooo~ he just looks like Shimotsuki Ushimaruuuuuuu" shit
My opinion based also on people crying about Kaido's flashback.
People here give too much importance for "backstory".
1000+ chapters and Zoro never NEEDED it. He always worked fine with what we had.
The actual journey that we, as readers, follow, should matter much more than some backstory.
A backstory should exist to explain certain motivations.
Zoro had his motivations explained already on his backstory.
Now, if we were to have something else, I would be open minded about it. Same with Sanji. The Vinsmoke plot was necessary? No. But it ended up connecting well with the Zeff plot. Maybe we can get something like that for Zoro.
But the key difference is that we needed Sanji's vinsmoke flashback to understand the story of his arc. I would be much more eager to get something for Zoro, had it appeared during acts 1 or 2.
Now? At the last 5 minutes of 2nd half? I think it missed its timing, but we shall see.