Of course everything is categorized, but not like we're talking about here. Give me an example or two of what you think is equivalent to placing videogame consoles into distinct generations that happens to be widely accepted.
X86 computers, first the 286, 386, 486, and then especially after Intel and AMD switched to named processors after the 486. You need to group them by generation to compare relative power between Intel and AMD counterparts, and keep them all straight.
But I would agree that numbered generations aren't ideal for videogame consoles, they'd be better grouped by their capabilities. But unfortunately, it's the categorization system somebody created, and it's the one everyone who talks consoles understands