There's a suspension of belief when it comes to movie-fate. I agree, all fate has to be controlled by writers. Because it is a fictional world no? But it is the premise that the only conflict between Jamal and Latika being together was time. That there was no plausibility as to why Jamal kept finding Latika. He seemed fine during the voyage on the trains with Salim. This was the highpoint of the film to me. The bond of brothers.
And you bring up a good point about it being a Love story. I think this is the source of my agitation. It had been something along the lines of 'City of God' and a tale of choices and destiny. Then the film falls into it's Quest for Latika and this pulled me away. Not because I hate love, but because I felt the bond between the brothers was unfairly overshadowed by this third musketeer. Who only expresses her true love at such a convenient time, while poor Jamal is busting his balls. But I guess...thats what love is all about.
Anyway, the cinematogoraphy, as you mentioned, is superb. I could almost feel as if I was in India. The whole hand-held aesthetic was touching; it's ability to glorify India's slums is a feat within itself no doubt.