Not sure where you get your timetable data from, but BRU to Ostend by train is less than 2 hours (unless you take a direct train that stops at every milk can along its way) and BRU to Ghent is less than an hour every hour. In Belgium everything is so close so no surprise that BRU is dubbed as the "National Airport" and LGG, OST and ANR are struggling to establish routes that last.