Don't worry, you're not alone. I feel the same way. Chrom is the more likely character, there's no doubt about that. A lot of people go so far to claim he's a lock... That seriously annoys me...
But I think Robin isn't given enough credit. I think there is a legitimate possibility that Robin could appear in the game. Not necessarily a huge one, but it's there. After all, Robin is one of the two main characters of Awakening, Chrom being the other. It's a rather interesting situation where there are actually two characters of equal importance that could be added to represent their game. The issue, of course, is that Robin is an avatar (though to be fair, he/she isn't a true avatar character, considering the character has preset characteristics such as personality and history). This in itself is not necessarily an issue though, due to the Villager also being an avatar character, and a much more customizable one at that. If something like Villager can get in, then Robin should be less of an issue. The main problem with being an avatar in Robin's case is that there is another main character who is not customizable, and as a result is the more marketed. That, of course, is Chrom. Naturally, since Chrom is the face of Awakening, and the most popular character from it as well, it seems, he's the most likely character to appear in Smash. However, Robin's saving grace is the apparent emphasis placed on uniqueness this time around. With every newcomer thus far bringing something brand new to the table, and the appearance of Rosalina, an unlikely Mario rep who introduces an entirely new playstyle, it would seem that uniqueness is an important factor for getting into the roster. This is where Robin wins out. Whereas Chrom's natural, signature abilities are the same ones already used by Marth and Ike, Robin's capabilities as one who can alternate between the use of swords and magic stand out as something unique that could be easily translated into the Smash environment. Like Rosalina, he/she may not be the most obvious choice, but what he/she can bring to the table is significantly more than what his/her biggest competition can offer.
It all depends on what Sakurai wants, I suppose. If having the most recognizable and marketed character from Awakening is what's most important, he'll go for Chrom. However, if he wants something that could offer something entirely new to the cast of Fire Emblem characters, and to all of the Smash roster, while still promoting Awakening, he'll go for Robin. Only time will tell at this point.
On that note, what do you all think of Robin's chances? Do they exist? Is he perhaps more likely than we give him/her credit for? Am I spouting out complete nonsense while thinking that it's logic?