Having posted in the past on individual LCC/budget/whatever airlines, I was very interested to see the proposal.
FFPs or not, some LCCs are bigger than legacy carriers. Within Europe, easyJet and Ryanair carry more passengers in their markets than the likes of BA, Lufthansa and the rest.
I would expect few FTers would spend much time on Ryanair, wizzair, FlyBe and the rest; however I can see that one on easyJet could be very useful. [On a point of accuracy, the easyJet business fares mentioned above are in addition to the normal fares, and BA don't charge for seat assignments other than on a voluntary basis for those without status.]
Therein lies the rub. Would a single geographical forum dedicated to all LCCs in the area be appropriate? It could get crowded. OTOH, a single forum with sub-fora for e.g. easyJet, Ryanair and others - along the lines of Flying Blue with separate sub-fora for AF and KL, or Miles and More with a separate sub-forum for LX - could work.
This is a European example. Other geographical LCC fora could follow the same principles. I support the proposal.