Essentially it is:
1) Girls like Monster High and Monster High is REALLY profitable
2) Girls and post-pubescent men like My Little pony
3) 1+2 == PROFIT

Which... may happen. I'm not so keen on the show itself but time will tell whether they can market these dolls or not. I really doubt Hasbro would be doing this without some serious market research.

Then again, they did release the Core 7 for that year or two...