Well, not everybody agrees on whether it's Cadence or Cadance. Technically, either is correct. I just go by the original Cadence (which was the spelling when they announced her), but through some reason or the other they changed their minds and changed it to Cadance far later. It's a mystery why thyey changed the spelling, and that's what we've been stuck with since.
I have no problem with those who spell it Cadance, but just remember that it used to be Cadence, and probably would still be if they didn't change it mysteriously.
iirc she was named after Cadince, the daughter of a Hasbro exec. Early publicity stuff is made while production is ongoing and always subject to change (like how Pinkie was a pegasus in some of the early promos, Selene was changed to Luna fairly late in the game, and so on), not to mention that it's usually put together by a separate team who isn't involved in the show itself, so unless there's some really good reason not to I just prefer to go with what they use in the finished product.
I don't blame you, and I have nothing against the choice. If I'm annoyed at anyone, it's Hasbro, not you. I just haven't had anywhere to say this before, and it's been bottled up for too long. But I really do not like the name change for 3 reasons.
1: It was sudden and unexpected.
2: That "a" just about kills me, as the grammar freak inside me screams out "That's wrong!". It seriously hurts my brain.
3: As far as I know, it was changed AFTER the premier of "A Canterlot Wedding" They shouldn't have changed it then.
I just noticed something though. Your picture spells it "Cadance", but the picture name is spelled "Cadence". Tricky.
I wouldn't call it "sudden and unexpected"; we had one very early promo spell it Cadence, and it's been Cadance ever since. It was not changed after the premiere -- all the promos, publicity materials, websites, and so on leading up to the episode airing spelled it Cadance. Or do you mean after the episode was made rather than premiered? If so, do you have a source on that?
I initially spelled it Cadence, I just forgot to change the title. I'll do that now, thanks!
...okay, I guess? I can't say it burns me up that someone spells a pretty pony princess's name differently. Maybe it's just Internet Tone, but you seem to think I'm getting upset or hyperdefensive or something, and I'm really not.
I hope you don't mind, I posted a link to this in my Facebook brony group. The resulting debate has caused a lot of laughs, actually. I did post a direct link back here so I figured it wouldn't be a problem :3