Bid'a or at least the Sunni defnition of it, is in my opinion a direct result of the closing of the gates Ijtihad, something I think you have mentioned before. The inability to adapt or innovate is, in my opinion, the single greatest reason for the stagnation of Muslim society and the end of the advancement of science that the Muslim world was abale to achieve up until the 1400's. Or as you put it, constipated… Wahabism is bid'a taken to the absolute extreme. I defnitely favour the Shia doctrine of Bid'a where only that which is absolutely clear in the Koran cannot be "innovated"; But Then again, you are down to individual interpretations of what is "absolutely clear". I think the very etymology of the word, in that it comes from jihad and the struggle to wrestle the truths from Gods commands clearly makes it a worthwile cause. One of the odditites that I have never really had the time to track down is how Al-Ghazali, who is so linked with the closing of the gates, was also such a proponent of Sufism. Sufism is very much a different path towards the divine but it is one I admire. Anything esoteric and mystical in nature requires dedication and time to truly understand it makes it inaccessible to a majority. And we know how the majority usually handle that which they cannot understand…. But its methodology and practices could arguably be said to be closer to true tawhid than mainstream Islam, and the teachings of its various leaders over time seem to reflect a group more at ease with itself and its religion than the more confrontational groups around it.