Just for the sake of discussion; you have probably not seen a non-dubbed film in ten years. Hollywood ADOs all its films, in the original American, because getting good sound quality at the shoot is not always possible. Besides, it's cheaper.
And frequently the dialogue is changed at the editing phase.
The difference is that the diector oversees the process, and it is generally the original actor who is trying to duplicate the emotions he was attempting to project at the original take.
European films, they don't necessarily even speak the same language on the set; they know it's all going to be redone.
A film well adapted (not merely translated) and well dubbed into a foreign language (yes, it can be done. I don't get to do it very often, because of budgetary considerations; doing it right takes time - time for the voiceover artist to absorb the emotion, the rhythm of his character, to make the text part of the action, rather than a label stuck on anyhow. And time is money) has only one slight disadvantage; it is not the film that the director intended. It can, however, carry the same message, and be a very good film in its own right.
Subtitling is cheap, but don't believe what they're putting up on the screen is an accurate translation. It could be; they don't have the lip-sync limitations we labour under, but then, during high density dialogue, it would distract from the action. So subtitling is frequently out of sync with the action of a film, and quantities of the dialogue are not transmitted at all. So, unless you can more or less follow the VO (sorry, "vérsion originelle" , I can't even think what it was in english) you're not seeing the same film as the director intended, either, though you are at least seeing it with the same actors.
Which doesn't change anything for the dubs of a feature film done in three days with five actors doing all the voices for a local television station; these are an abomination unto the muse of the seventh art, and should be punished with something lingering and preferably non-fatal, so the perpetrator can suffer many years of watching "terminator" movies dubbed into spanish or serbo-croat.
But it does mean that, without a resonable knowledge of the language in which a film was shot, you're not reading the book.
You're looking at the pictures.