"Another advantage of a constant 1g acceleration is that it would allow the pilot to make very long journeys. To an observer on Earth, such a ship would take hundreds of thousands of years to reach the centre of the galaxy. Thanks to relativistic time dilation, however, the pilot would be only 20 years older on arrival. So, for the pilot, the centre of our galaxy is only 20 years away!"

The reference frame of the PILOT is the only one that matters- if one can go somewhere in a matter of decades, and one expects to live many decades, it might well be reasonable to travel. Look at soem of the voyages by sail- a WHALING TRIP of several years ( or several) was not considered uncommon, with a lifetime of 70 years total.