IFR general aviation aircraft under radar control; but issued direct clearance to ZACKS for the SBA VOR/GPS 25 approach procedure; voiced concern regarding the requirement to complete a procedure turn; alleging that both pilots and controllers are confused as to the turn requirement.

Narrative

On IFR clearance from ZZZ to SBA. Final way point in that clearance is KWANG; from which a straight-in approach via the SBA VOR/GPS 25 approach is indicated. Received radar vectors for sequencing prior to KWANG; then 'proceed direct ZACKS (the FAF and also an IAF); maintain 2;100 until established; cleared GPS25 approach.' Shortly thereafter; I was instructed to contact the Tower. Per AIM 5-4-9; a procedure turn is required with this clearance. ATC provided no radar vector to intercept the final approach course; nor did ATC assign a 'straight in approach.' Considered as an IAF; ZACKS does not have a 'NoPt' indication; vs. KWANG; which does. The fact that the assigned altitude (2;100 FT) was below the 3;000 FT floor of the outbound procedure turn segment aroused my suspicion. I queried the Tower Controller; who informed me not to perform the course reversal and proceed straight in. I was able to do so safely and landed without incident. In my opinion; this misunderstanding could have resulted in a very serious situation. Were another aircraft cleared straight-in for the same approach behind me; and had I performed the course reversal; there would have been two aircraft; in IMC; heading in opposite directions; at the same altitude; following the same highly precise GPS course. In discussions with others; confusion over procedure turns in radar and RNAV environments seems surprisingly common; both among pilots and controllers. Similar to the often redundant altitude clearances (e.g. 'maintain [altitude for which you were already cleared] until established. . . .'); perhaps ATC should consider including 'cleared via straight in' or 'cleared via procedure turn' in all approach clearances to obviate similar misunderstandings.