What is this? This means you have a strong tendency to coin the main character as an uke if the seme/uke role isn't defined. This is something I noticed for some time and it is kind of interesting to think of.
I recently watched Tiger and Bunny and I view Kotetsu ojisan as an uke. He isn't particularly uke-ish. Actually, he sometimes seems like seme. Actually, I could blame on my other fetish of liking older character as uke(年下攻）. Bunny isn't really seme-ish. He isn't Kichiku（鬼蓄，腹黑） nor does he have particularly strong character. He breaks down and couldn't keep control of his anger.
Another example(main chara that is more seme than uke) I could think of now would be Gintama, I like Gin-san as uke even though he's super seme, super strong. Actually, I'm not really into pairing in Gintama. But I love Gintama like crazy. It's the only anime I feverishly pursue every week now. All others I read manga. Ahem, out of topic. In my mind, I kind of have a thin block Gin-san as seme. It's not like I'm totally against it but I'm not loving the idea.
This applies for all shounen titles. I pretty much view all of the main characters as uke. LOL
I think this kind of thing happen because when you read a BL novel or BL manga, the main chara is always uke or at least 80% of it. So I kind of got influenced with this idea. This is another thing worth pondering over. Why, mostly the main character is the uke? I think it's because mostly uke have richer emotional feelings/monologue to sympathize over. I think it is a mental thing. When you don't know what the seme thinks, he'll look more 'cool'.(Actually, like Junjou Romantica and a lot of BL novels, their is a lot of seme's POV too without much problem but they are still not the main character or their POV only set in the extra part of the novel,番外) Actually, it happens in shoujo too. Mostly, the main chara is the girl.
Do you have this problem?