The comparison of the "6th" council to Rama I's council looks reasonable. Both happened after tremendous political change and handover of power. However, I wonder if the council called in Rama's case was not also intended to build up some good kamma to dilute the regicide of his predecessor? Hmm, perhaps coming full circle, now that Thaksin's clan might be doing something to bring Taksin's curse on the dynasty to fruition....
I think (leaving aside all suspicions of a Dhammakaya conspiracy or a Thaksin plot), what catalysed the interest in a new critical edition of the texts was the discovery of hitherto unseen hordes of manuscripts in the North, the former Lanna stronghold. Pop into Google and you'll find a flurry of academic output on these finds, ranging from textual analyses, orthography, manuscript production techniques etc etc. Here's a nice summary from Oskar Von Hinüber, also on the Dhammachai advisory board -http://www.siamese-heritage.org/jsspdf/ ... ailand.pdf
The Thai (or the Lannas) can now claim to have the oldest dated Pali manuscript; perhaps this source of national pride was one of the motivators?