ACR ON APCH TO LAS QUESTIONED ATC'S APPLICATION OF WAKE TURBULENCE SEPARATION PROCS.

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LAS VEGAS APCH ATC IS UNDER THE WRONG IMPRESSION THAT WAKE TURB SEPARATION INTERVALS SPECIFIED IN THE AIM; AND REPEATED IN OUR ACR'S FOM ONLY APPLIES FOR IFR OP AND NOT FOR VFR. THIS WAS STATED TO ME BY ITS OPS MGR MR X. ATC DIRECTED MY BREAK OUT OF THE FINAL APCH SEGMENT AFTER I INSISTED THE NEED TO REDUCE AIRSPD TO OBTAIN REQUIRED SPACING BEHIND A B757. THAT ACFT WAS APCHING THE PARALLEL RWY (1L) WHICH IS SEPARATED LESS THAN 2500 FT FROM MY ASSIGNED RWY (RWY 1R). THE BREAKOUT ACTION COST OUR ACR 1500 LBS OF FUEL AND 10 MINS OPERATING TIME. THE LAS VEGAS ATC OPS MGR; MR X; SAID 'I NEEDED TO REQUEST WAKE TURB SEPARATION EARLY.' WAKE TURB SEPARATION STANDARDS ARE NORMALLY AUTOMATICALLY APPLIED BY MOST ATC; IRRESPECTIVE OF WX; FOR LNDG AND DEPARTING ACFT USING THE SAME RWY; PARALLEL RWYS SEPARATED BY LESS THAN 2500 FT; AND FOR SOME SITUATIONS; XING RWYS. THE PLT DOES NOT NEED; OR IS REQUIRED; TO REQUEST THE SEPARATION. I WAS ADVISED THE B757 WOULD BE ON THE PARALLEL RWY; BUT I DID NOT KNOW IF THAT ACFT WOULD BE IN FRONT; BEHIND; OR ABEAM MY PLANE. IN ADDITION; I WAS NOT YET ASSIGNED A LNDG RWY. THE MOMENT I WAS ASSIGNED A TURN TO BASE LEG; I REALIZED THE SITUATION AND NOTIFIED ATC OF THE CONFLICT. ATC CLRED ME FOR A VISUAL APCH AND REFUSED MY NEED TO REDUCE BELOW THE ASSIGNED SPD OF 170 KTS TO OBTAIN SEPARATION. SO; WHAT IS GOING ON HERE? WHY WAS I SEQUENCED OFF THE FINAL APCH SEGMENT DUE TO MY NEED TO OPERATE A SAFE FLT? MR X SAID I HAD ACFT BEHIND MINE. SINCE WHEN IS A LEAD ACFT ROUTED TO ACCOMMODATE FOLLOWING ACFT? CAN'T THE FOLLOWING ACFT ALSO SLOW OR DELAY ITS TURN TO BASE LEG? HAS THE WAKE TURB PHENOMENON OF THE LAST 40+ YRS GONE AWAY? DOES IT ONLY HAPPEN IN IFR CONDITIONS? THE IRONIC PART OF MY PHONE CONVERSATION WITH MR X WAS HIS COMMENT THAT 'OTHER PLTS ACCEPT REDUCED SEPARATION BEHIND B757'S AND HEAVIES ALL THE TIME.' HE DOESN'T UNDERSTAND THE PROB.