I can understand Kirk55555
's feelings. It's hard to watch one of your favorite characters being forced to say and do things against his will. I have similar feelings about storylines in which a long-time character is framed for murder. Some storylines are just difficult to enjoy (even when the writing/acting/directing is done well).
Personally, I found Londo's closing storyline (including the Centauri trilogy) a fitting way for a rather dark character to find some level of redemption. It's not for everybody, though.