>>25975415Because better graphix = better game.
But in all seriousness who knows. Maybe they think that 1998 HL is too "outdated" or ugly looking, or maybe they think that because it's an old game they'll have to go through all that "labor" of installing a fanpatch, though thankfully Valve makes sure their old games are very playable on modern OSes unlike other devs like Rockstar and how GTA3-SA/Manhunt/Max Payne need fan fixes in order to be playable or not run into annoying issues.
It could be that they've heard about Xen being bad and assuming the remake fixes a ton since it's being sold on Steam, though Black Mesa stretches it out and adds in its own issues.