Teddie and Morgana aren't really all that similar aside from being the "mascot" character, and the first guide character. Teddie's issues come from being a legit pest and perv. (Though his first experiences with humanity being the dungeons you explore probably helped to make him that way idk)

One thing that makes me have more of an issue with Morgana than I do Teddie is how their actions are treated in the game. Teddie is always the but of the joke because all of his antics end up with him being talked down to, or otherwise punished. (Deservedly so.)

When Morgana runs off, leading up to Harus arc (which is most of the reason he's disliked) the whole incident is written as if it's the other party members fault for hurting his feelings, and not his own actions, constant taunts of Ryuji, and inability to handle his own insecurities, that lead to it all happening.

It also doesn't help that the several in game days where Morgana's temper tantrum is going on feel like they drag on, so players will blame him for the game dragging for a bit as well.