Confusion reigns as B737NG flies GEELA TWO RNAV ARRIVAL to PHX. ATC failed to issue 'descend via' clearance yet appears to expect flight crews to meet procedural speed and altitude restrictions.

Narrative

We were filed/cleared to PHX via the GEELA2 Arrival with a flow time out of LAX. Enroute we were given a number of assigned speeds. As I remember; ZLA ended up giving us normal speed direct SCOLE at FL250. I do not remember if LAX cleared us on the GEELA2 Arrival and there was no speed assigned. Nonetheless; I knew the GEELA2 was the arrival that would be flown. We were switched to ZAB. I am confident that ABQ did not give us the GEELA2 Arrival. We crossed SCOLE as assigned (and 300 KTS per the GEELA Arrival). Past SCOLE; ZAB cleared us to cross the GEELA fix at 250 KTS; 11;000 FT. My First Officer interpreted this as deleting the HYDRA fix restriction (280 KTS; 13;000 FT) and he deleted the restriction from the FMC. I agreed. The resultant FMC descent was programmed at ECON (261 KTS). At approximately FL200 and as we were slowing to ECON; ABQ asked what our speed was. I believe it was 265 KTS. ABQ then gave us notice of possible pilot deviation with a phone number and then cleared us to 'descend via the GEELA2.' I read and am aware of speed restrictions on the GEELA2 as well as past speed deviation problems. Still; on this approach; I was confused as to which procedure took precedence. 1) The flow time restriction with various speeds assigned enroute (by ZLA) culminated in 'normal speed' descent into SCOLE made me feel I had desired spacing into PHX (numerous slower speeds issued to preceding aircraft on the arrival; but not us). 2) The (perceived) lack of arrival clearance and definite lack of 'descend via' clearance; combined with the elimination of an enroute airspeed/altitude restriction (at HYDRA) made me feel there was no traffic immediately behind me and that we were flying the ground track of the arrival but the 'whole' arrival (with airspeed restrictions) was not required. 3) The deletion of the HYDRA restriction in the FMC led to ECON descent guidance to GEELA and items 1 and 2 above combined with the desire to save fuel resulted in our interpretation that ECON speed appropriate to fly. My phone conversation with ABQ Center Controller was cordial; non-confrontational; and left me with the impression that was he viewed this as an opportunity to 'spread the word' about GEELA airspeeds; not as a violation. He mentioned a trailing aircraft (I did not know was there) that had 100 KT overtake (!?) on me and that flying assigned speeds prevent compression on the arrival. The conversation also left me with 2 other things: 1) ZAB expects GEELA speeds to be flown PERIOD (even if clearance deletes fix restrictions). 2) They don't feel 'descend via&' terminology is required to achieve this. Currently; the objectives of high volume station arrival ATCs and the Company are at odds. ATC wants to service as many aircraft as quickly as possible so they want aircraft to fly fast to a point and slow fast for landing. This 'fly fast -- slow fast' procedure is certainly not fuel efficient. The Company (and me); on the other hand; wants RNP now; but must settle for 'ECON when able' for the time being. The following are suggestions that may help the less astute (like me) better prioritize: 1) Clarify Company's guidance on ECON speeds versus RNAV speeds so that we fly every RNAV arrival only at depicted RNAV arrival speeds or as assigned by ATC (i.e. no ECON). ECON speeds would only be used on enroute descents; descents prior to the first fix on an RNAV arrival; and non-RNAV arrivals. 2) Emphasize use of more definitive ATC terminology. Arrivals accommodate many different aircraft operational capabilities so just 1 approach for all won't work (just yet). So ATC routinely has to modify airspeeds and occasionally altitudes (LAX and PHX are bad; LAS is good -- amazing!). The result is that while we fly many RNAV arrivals; we rarely fly them as depicted. This conditions me to fly the approach ground track and altitudes; but feel depicted airspeeds are not as important. Throw in guidance/desire to save gas at ECON speeds and I end up with 'flywhat I have to -- save when I can' approaches (in obvious conflict with ABQ's view). Perhaps more emphasis on ATC 'descend via XXXX' or 'descend via XXXX except&.' terminology would help since it more clearly delineates the specific parameters expected by ATC.