We have all asked for improved graphics, bigger environments, a more realistic looking water surface, more detailed vessels with more functions etc.
Of course this requires more computing power. And of course this can't be achieved with an old machine or an office laptop. That is the price of progress - the most actual software requires at least relatively actual hardware. Otherwise i could have kept my Amiga. Laptop users - except owners of extreme expensive gamer models - must always be prepared that a game won't run properly.
When I noticed the requirement changes I was disappointed, too. But I remember months ago, when the first screenshots appeared, I already stated that I was concerned about if my PC could run SSEx. Even with the now known system requirements I'm not sure if my machine can run the game properly or not, as I don't know if my processor is "equivalent" or not. I just have to wait until a demo version is available.
By the way, as you mention Virtual Sailor, you might have noticed, that its successor, Vehicle Simulator, requires better hardware, too.