Will Iota adopt brain wallet similar to Nxt?
Yes. But the seed will be forced to 81 latin letters and '9'. Nothing stops other devs from using another approach, of course.
why the fuck not 12345678 ?
I'm going to read a bit between the lines here but IOTA is built to work efficiently with a ternary (as opposed to ye traditional binary) processor that CfB is working on. I would assume that since there are 26 letters in the English alphabet, adding an additional character to the list would make a well rounded 27 (3^3) available characters. So 3 trits (think base-3 bits) can easily represent one character in the pubkey. By adding one more character to the usable alphabet you don't have to filter out or validate that one, unusable value. All possible 3-trit values can be used for an 81-character pubkey.
But why 9? Since 0 and 1 tend to be thrown out of specialty character sets that may need to be read by humans, this would leave digits 2-9 as possible numeric candidates for the 27th letter of the alphabet.
Being that this is for a ternary system, we could narrow down the numeric character subset to values "2", "3", "6" and "9" as best possibly choices for stylistic reasons.
Since 9 = 3^2 and as CfB mentioned is the position of the Iota in the Greek alphabet, it makes sense to use the character "9" as the final letter in the IOTA pubkey alphabet.
Again, I'm reading between the lines but this is likely the logic I would have followed if I needed to create a ternary-friendly alphabet consisting of a minimal subset of characters for pubkeys.
and I very much like the name. 
