So? I consider System Shock 1 to be a classic, but for today's standards it's still obsolete, same for PST. And just because there're a lot of fans who still enjoy old games doesn't mean these games should be remade over and over again. Design ought to progress as does technology with time.
Apart from System Shock 1's interface, how do you feel PST and System Shock 1 have been improved upon by more recent games in terms of design? System Shock 1 in particular, has pretty much every FPS I've played in the past 4 or 5 years, beat, in terms of design. Also, In terms of choices and consequences, PST leaves most modern RPGs behind.