Why is a procedure turn required if you are more or less on the final approach course?
Read that other question again.  He was approaching from the SSW and made an assumption based on the approach segment from AUGIE.  He wasn't actually on the AUGIE-BEJCY leg as it would be impossible to be there if he were approaching from the SSW.  

His clearance was "Direct BEJCY cleared for the GPS 01 approach".  That clearance, in lieu of any specific instructions about the procedure turn, requires that the procedure turn be flown.  He assumed that because he was roughly on the extended centerline of the runway SSW of the airport that he was exempt.  However, there is no charted course there labelled "NoPT", so his assumption was incorrect.

Back to your question of why someone flying from that location would have to fly the PT, and the answer generally boils down to "TERPS".  The leg from AUGIE can be flown at 3000 ft while the area minimum safe altitude is 3100 ft.  It is very likely the minimum enroute altitude over that area is higher than 3100 feet.  This means a pilot that is using BEJCY as the IAF may be considerably higher altitude than 3000 ft.  On this approach you ideally want to be at 2500 ft by the FAF at CUCTO.  If you are approaching BEJCY from any direction other than AUGIE this means you cannot start your descent from whatever altitude you are at down to 2500' until passing BEJCY.  The procedure turn is not only for course alignment but also to descend to the procedure altitude from the enroute environment.