I think it gives Columbo a fuller character. A real detective would have to take a different approach and tactics with different criminals, maybe 99% would be the same way, but not 100%.
I agree with Stephen. I know a LOT of people hate this episode, but I quite enjoy it. Don't misunderstand me, I like the established formula and Columbo's usual methods, but I also liked seeing him out of his element, with time pressure and no prep to sweat... Just the lingering abject terror of a relative (in-law, but anyways) meeting a foul end. Yes, it's unusual: but that doesn't make it any less enjoyable!