On TCAS, there seem to be two different points being muddled.
1 - An assertion by some posters that this incident supports a programme to mandate TCAS (as in the certified system in airlines) in all aircraft. - Nigel and Farrell make make important points that TCAS is not a panacea and would have massive issues as it is the whole system/process. It is not just a box of tricks - even though some may use it as such. (besides, mandating #50k and probably 200 lbs of kit and power into most GA aircraft would end the industry)
2 - IO540 (and others) point, is that having GA style traffic information can be a really helpful thing in helping to spot traffic the Mark 1 eyeball didn't. It isn't a system, all it is help in seeing and avoiding - and just like all the other parts of the see and avoid system, it is up to the pilot to work out a resolution and execute it.