I think the only reason why they changed SAM is because people that raid with it barely Midare'd.
They would just build 3 Sen, hakagure'd then spam Shinten, then Midare if Hakagure is on cooldown.
This made SAM really flexible but it put what's supposed to be the Job's main defining move on the back burner for an OGCD spam.

New SAM pretty much changed that by putting more emphasis in the Midare rather than the Shintens because of Tsubame.
The only problem is that SAM isn't that flexible anymore, and they have to follow a strict 1 minute rotation so Midares can go into Tsubame with no drifting.

IMO, I really like new SAM. It's really comfy, knowing that you just have to follow a 1 minute. It's kinda like Stormblood MCH.