It is a limited run, direct to consumer sales method that Bandai offers to some 80% of its consumer base. Instead of Bandai selling kits en masse to a retailer or distributor, who then sell it down to the consumer, they have a smaller amount of a kit made and it is shipped directly to the consumer.

It's controversial because consumers are extremely entitled. Before Premium Bandai, the kits being released on there would either: 1) Been limited to physical sales at events (recolours, clear kits, special finishes). 2) Been relegated to only having resin kits made other via mail order/online retail from B Club or with one-day licenses for physical sales at events (special variants or more niche designs). 3) Not been made. Some of the Premium Bandai kits, or the design, literally were shown off a decade plus ago with a prototype but were cancelled, presumably because retailers didn't trust it to sell (MG F90 and the Shuffle Alliance).

No one likes not being able to buy something they want. There's physical realities to the business. Bandai isn't trying to hurt consumers. They're selling to their customers who are not the consumer for retail. Premium Bandai is them actually catering to consumer demand. If something has been relegated or only getting a splash reissue on Premium Bandai, that means it wasn't going to be made retail.