War day last 24 hours so that there's no problem with international clans, partly. If the war ends in a tie and there's 1 hour left... What about the people who's sleeping?
Also the likelihood of a clan to win does not depend only on the top bases, but ALL of the bases. That's why a clan with, say, 1 TH 10 can still defeat another clan with 3 TH 10s. Because all of the attacks have the same weight in stars. If it ends in a tie and to win you depend on top bases the conditions wouldn't be equal.
I do agree with the idea of a tie breaker... I like the "clan with more 3 stars" idea or something...

