Because lite works. Its a lite version of the switch which implies less features or cuts in general.
Implies less features yes.
It doesn't imply that the feature that the device is named will be cut.
This is like saying it would make sense for the DS Lite to only have one screen. Because "lite" implies dropped features, and fuckall if "Dual Screen" is in the name.
Nintendo is selling products to the masses, not people on gaming forums. TONS of people will buy this expecting it to "switch". While a bunch of guys on high horses on gaming forums will say its their own fault for not researching the product, the fact is Nintendo doubled down on this messaging to make the first Switch a success and are shooting themselves in the foot.
This is missing something right in front of their faces, in hubris, like when the masses couldn't tell the WiiU was a new console and not just an add-on to the Wii. Yeah everyone here knew exactly what it was, unfortunately Nintendo needed to market to the other 80 million people. They took for granted their own importance, assuming everyone in the world will appreciate the gravity of a new Nintendo console launching and go out of their way to read up on it or whatever.
It will still do great, but result in a ton of confusion and aggravation. Many customers will feel misled or tricked. Not a good thing.