It would be awesome because both me and you will notice a different when moving everything to a different game engine. And then, mods or fangames will be easier to create than before, based on the feel you experience when you play Half-Life 1.
Its better to see the game in different engines than just goldsource or source engine.
Its like remaking half life in game maker.
All textures/models/sounds/ai/maps/scenes/feel is ripped and converted into a game engine that is not made by valve.