I like your thinking. And that can work for both Super Mario Bros and New Super Mario Bros. It always bugged me that New Super Mario Bros 2 was called that, since it's actually the the third one in the series.
Or how Wario Land 2 is actually third since VB Wario Land released before it. Though an argument could be made it's more of a spin-off (either that or Nintendo was too ashamed to actually acknowledge it. It's probably that)
I can understand them being ashamed of the Virtual Boy, but not Virtual Boy Wario Land. That game slaps! It's a shame most people don't know it exists. If we ever get a remake of VB Wario Land, they should call it "Wario Land 1.5"
I didn't finish it but I will say I really dig how Wario controls in this game. The Shoulder Bash never felt as good as in this game. Wario Land 1.5 sounds about right too.
It always bugged me that New Super Mario Bros 2 was called that, since it's actually the the third one in the series.