Tell me, out of the 10 million people who bought and played Brawl, how many do you think knew who Ike was before he was confirmed in Brawl=???
Maybe like 10% tops. As big as Fire Emblem is, it just isn't a series everyone knows the main character of like say Sonic or Mario. Plus, the main characters switch like every game. The only 2 Lords to be the main character in 2 games are Marth (4 of 13 games) and Ike (2/1 and a half games out of 13).
Also more games doesn't equal better sales. The original Star Fox alone has probably outsold the entire Fire Emblem franchise. What that means in correlation with smash... I have no clue as to the total effects. But that's the truth that it did.
By "Nintendo All-Stars" I mean characters you think of fairly quickly when you think of Nintendo. You just close your eyes and you see them next to the Big N logo so clearly.
I don't know about you, but the Smash 64 original 12, Bowser, Peach, Zelda, Dr. Mario, Ganondorf, Child/Young/Toon Link, Game & Watch, Marth, Wario, Diddy Kong, a/the Pokémon Trainer, Mewtwo, Lucario, King Dedede, Meta Knight, Pit, Olimar, and the Villager all come to mind.
Of the prime candidates left, K. Rool, Ridley, and Miis most easily fit into that category with those names IMO. Heck, they belong with them IMO.
Granted, not every Nintendo-owned character is in that "category" (see: The Ice Climbers, maybe Ike) but the bulk of them are just that.