Sometimes those reasons are a bit dumb. Many times it's called "thinking for the future" or something, when it couldn't be clearer the realm just doesn't have the guts to make that enemy realm's characters/players hate them for a long time. Of course it's sometimes interesting to wonder just how long term some players think. BM's been going on for what, 8 years? That's already a pretty long time, but just how long do they want their plans to take? I wouldn't place any bets on any 10 year plans because you're probably better off investing in some stocks in the hopes that the economy gets better in 10 years. Maybe 5 year plans are a bit more credible, but even then, BM would be 13 years or so. That's a pretty long time for a specialty online game.
Just for the humiliation of the beating, that realm's nobles are likely to hate them for a very long time. And in a lot of cases, it's not the first time war broke out. Take Riombara and Enweil, for example. I don't think the old blood in Enweil really were out for Riombara's extermination, but due to Riombara's historical hostility against Riombara, a significant portion of Enweil wanted to do away with her once and for all, to finally be able to "move on to other things". People tire of fighting the same enemy over and over, I would assume. Pity can only go so far before the patience that supports it crumbles.
