They are becoming even more valuable with the advent of modern glass cockpit aircraft, as there are inumerable failure modes that cannot be recreated in the real aircraft. In fact, there are many cautions, warnings and display symbols that a pilot will never see except in a simulator or in the event of the real failure.
Old or new, the benefit of LOFT and CRM assessment should never be underestimated, and one aspect of simulator based checks that is never represented in the aircraft: the P2 is a normal pilot, not a training captain (no rude jokes required!). Therefore, when a failure occurs the crew react as a real crew (fumbling through checklists etc) not the false situation that exists with a TC acting as P2.
The other benefit, generally speaking, is the simulator availability is more predicatable than using an aircraft; not weather, customer or serviceability affected (albeit sims go u/s too.)
I think, that as long as within sensible limits, one should not get to 'hung up' about how precisely a sim replicates some emergency behaviour. At the end of the day, it's your reaction, response and airmanship that is being assessed/trained.