It's not the name that's the problem, it's trolls deliberately spelling the number out, so that it says "bone". Did people call the Xbox 360 the "XThreeSixty"? No, it was just the "360". There are plenty of shorter alternatives than "Xbone" so shortening it down isn't the excuse. There's X1, XOne for examples.
X1 = Xbox 1 (the original)
Xbone = XBox One
The official name of the console is "XBox One", with the "one" spelled out. The official name of the 360 is "XBox 360", not "XBox Three Sixty" which is why no one short-hands it by spelling out the numbers.
Also, Microsoft bought the domain name "xbone.com" so it's now an official abbreviation for the console, whether the "team" likes it or not.
On topic, both slogans are ridiculous in my opinion. The "real" one doesn't make any sense, and the "beta" one implies that the console is still in development and will go into beta in the future. i.e. those who buy it will have to deal with bugs and other beta-related issues. It just doesn't imply anything good to me. And, yes I know that's not the case, but this is an ad targeted at the general public.