I think people are lazy in their dismissal of remakes. There are many classics that are themselves remakes, either regular remakes or 'reimaginings' (such as samurai films reworked as westerns).
I think reimaginings are somewhat different - The Seven Samurai and The Magnificent Seven are totally different films (even if they are the same story).
The reason that remakes are so easily dismissed is that there are very few examples of a remake being better than the original (and in most cases, they're considerably worse). There are some decent remakes: True Grit and The Thomas Crown Affair (that's one where the remake may actually be better) but the vast majority are dire: Alfie, The Italian Job, Get Carter etc
There was even talk, a few years ago, of remaking Casablanca - thankfully, that idea died a death.