Though I'm not nearly as learnéd as some of our members here, I'll offer my perspective.
From what I've gathered, samma-samadhi is generally defined in the suttas as the 4 rupa-jhanas, sometimes with the 4 aruppa jhanas included as well. "And what, monks, is right concentration? Herein, secluded from sense pleasures, secluded from unwholesome states, a monk enters and dwells in the first jhana, which is accompanied by initial and sustained application of mind and filled with rapture and happiness born of seclusion..... (and the other 3)"
This passage occurs many, many times. Reading through the suttas and seeing how many times jhana and right concentration as jhana is mentioned, I find it hard to believe that jhana was/is not meant to be a vital aspect of the path.
The problem with the contemporary split between samatha and vipassana practices stems from the issue of the commentarial/abhidhammic jhana, which requires a depth of absorption that few can reach, though this definition is accepted in mainstream Theravada. Because of jhana being put on a pedestal above the reach of most, it makes sense that an alternative had to be developed.
But the suttic/earlier jhana most likely is not a state of complete absorption, completely secluded from the senses and thrown into a trance. It's a practical method of calming and sharpening the mind in order to utilize it for the gaining of insight, as well as helping to wean the mind off of sensual pleasures and help dull the emotional aspect of dukkha, and with this calm clear mind, work on the wisdom that will get rid of the root causes of dukkha as well, which can be done while in the jhana (Look at the Anupada Sutta for an example of Sariputta doing just that). In other words, samatha and vipassana can be practiced in tandem, no need for the split.
If you haven't read it, there is a particular article by a member of websangha that covers this subject really well, highly recommended. http://www.forum.websangha.org/viewtopi ... &sk=t&sd=a