For me, there are two sides to this:
1: The interface seems genuinely more user-friendly, at least for mobile users. HOWEVER...
2: I find it just a little bit worrying that they would make a separate store site just for the cash shop in the game. I mean like, previously the optional items thing felt like a sidetracked extension of the game, due to it being part of the mogstation service, but now they're devoting extra resources just to market the microtransactions. With weird sales pitches like "RECOMMENDED ITEMS" or "MUST-BUYS", no less. Like I said, it's... worrying.