It is not pointless... A few years ago, Ford stopped producing the Tarus full size sedan. They revamped the full sized sedan line and produce the Five Hundred. The Five Hundred sold very poorly, despite being a fairly highly rated vehicle. A couple years later, Ford again rebranded the Five Hundred to be the Tarus. It sold like hotcakes. People didn't buy the Five Hundred because nobody recognized the brand.
So to with Pentium, and a lesser degree, Celeron. People know what to expect from a Celeron. It is going to be slower and cheaper than the main products. People know about Pentium too. That brand is associated with mid tier performance. Intel spent a lot of time marketing those 2 brands in the past, and they are living off that brand recognition.
Power users will always know what is what. But the average consumer has never heard about AMD, let alone Fusion (thanks again AMD Miracle Marketing)... They have all heard about Pentium and CERTAINLY Intel.
EDIT
And as a side note, these Celerons are not your pappy's CPUs: These are SANDY BRIDGE or maybe even IVY BRIDGE based parts. These use the latest architecture, and are either crippled or binned into these cheap ultrabook segments. Even a crippled Sandy Bridge can run circles around most Core 2/Phenom II based chips. Just look at the Newegg reviews on the bottom tier Sandy Bridge based Celeron. It is 5 solid eggs... People who buy these chips expect to get a crappy product, yet are often pleasantly surprised at just how good these SB Celerons are...