Sega, as a third party developer, has different expectations on succes for a game. Also there is no evidence the budget is the same. Development costs decrease with sequels, particularly because assets are reused/modified.
And you think nintendo expectations are lower than sega, for all we know, their expectations could be larger than sega. Even if bayo 2 was cheaper to make than the first one, it couldn't be that much different and again, the game was overtracked in US. Right now it should be at 500k at most because it could be overtracked in Europe as well, and by the looks of it, the legs are horrible at this point so the chance to reach 1 million is very unlikely. Like I said before, if nintendo asked 250k sales for a game like fire emblem that doesn't look demanding at all, you know that 500k or 700k is too low by nintendo standards for a game like bayo considering the development costs behind it. Nintendo doesn't like to break even, they mostly try to go for decent profit at minimum.
Nintendo, as a hardware manfuacturer, has extra benefits which Sega does not (as a third party publisher.) For starters, diversifying the software found on their hardware can lead to long term benefits in the sale of said hardware, and then, in turn, the sale of their software. Sega cares solely about profit maximization, and if there is a huge opportunity cost (even if they can make a profit off Bayonetta) they will not publish the game.
The bolded is speculation.
Underlined shows a lack of what induces costs in a game. Asset quality and number are the main determinations of whether or not a game will cost a lot. Fire-Emblem has animated cutscenes, and dozens of characters that need to be designed. Just because the graphics technology aren't pushing the boundaries does not mean the game is cheap to make. Bayonetta, on the otherhand, had assets already designed, and likely also had a fully functioning engine which the developer (Platinum games) utilized. The costs of HD development were already subsidized by Sega with the first entry. You don't know the development costs, so stop acting like you do.