The new Commercial Bellisseria shops are very attractive to prospective Premium Plus subscribers, but because they come with no fee nor tier impact, they will be demanded by every single Premium Plus subscriber willing want to "play merchant" in exchange for a 2048 m² parcel they otherwise wouldn't have at all.
This will use a lot of resources, and also dilute the value of parcels for more intentional SL merchants who might otherwise enjoy being part of a fledgling geographic community of Belli shopkeepers.
At the same time, there's a whole lot of empty Mainland, with more than a few of those prospective Premium Plus subscribers who might well prefer taking on an additional 2048 m² bonus tier (in addition to their current 2048 which they can spend on a combination of Linden Home and/or Mainland).
I believe the mechanism for offering this alternative should be pretty simple, and undoubtedly more cost-effective than adding sufficient Commercial regions to meet demand to the satisfaction level expected of any "premium" service.