Because in the '60s and '70s it was the best job in the world bar none. And I guess that past glamour still carries some weight with people who are on the outside of the industry without much knowledge, who want to get in. All that past pomp and circumstance is pretty much gone now, except in the minds of the last few old-school "A" scalers in the training department who still think Cathay invented aviation and Chuck Yeager should be grateful for a CX SO job.
These days it looks to me like it's just another Chinese airline, with a sub standard T&C package, 20+ years to command, Maoist industrial relations, and HK is a filthy polluted expensive over crowded mega-factory city.
Horses for courses, and yes of course you'd be crazy not to take it if you were a minimum-wage turboprop jockey and young enough to not mind the 2-decades-in-the-right-seat thing. However if you already have decent jet time from elsewhere, then I really really can't see the CX attraction any more.