People are just thrown off by the atmosphere of it, i mean the main SMT games always take place in a modern Tokyo, but usually in a sort of uninviting setting, like after apocalypse or something. However they are going with a style more similar to the SMT spin offs, such as Persona, Devil Survivor and Strange Journey, wich isn't bad, but the very first teaser had hinted at a main series crossover.
Now with that said, the game does look very promising and it's, along with Xenoblade Chronicles X and Zelda U, one of the most ambitious projects for the Wii U.
However you can tell from that trailer that the style of the game just isn't what people were expecting at all, it's different, and it's only natural that people are thrown off by it, after all, a first impression is always very important.
They're just a bunch of pansies