Much of what you say is very true, yet I feel the need to prolong the debate just a little bit. I'm aware that the thread is on transportation links to the airport rather than the airport itself; I won't make any more ideological comments after this one
Are my attitudes NIMBY? Of course they are. Is NIMBY always such a detestable thing? Not necessarily: only if those attitudes stand in opposition to progress and block the construction of infrastructure that is necessary. Back in the 1960s and 1970s, those men and women who opposed the Spadina Expressway would have been lambasted as NIMBYs, and yet we all know now how vital their work was in keeping Toronto's downtown the vibrant area that it remains today and congratulate them for their struggle. So I don't mind being a NIMBY if it means doing what I think is right. The key is that the Pickering Airport is not a necessary evil, and opposition to it should not be thrown out as simple NIMBYism. It's about trying to minimize the damage to our environment and natural heritage, preserving our communities' health, and in fact also spending our tax dollars wisely.
Pearson has much spare capacity. Hamilton has capacity and room to expand. Waterloo has room to expand (and that's all the better if HSR is ever realized). Yes, it would be nice to have an airport in the eastern end of the GTHA, but there's no use in destroying so very much farmland and spending so very many taxpayer dollars to build an entirely new airport in Pickering for which there is no, and has never been a, business case.
To link the east of the GTHA to its western-concentrated airports, our money and effort would be far better spent in upgrading regional and local transit to the airports that do exist. That means full GO service on all lines, to link the GTA with Pearson, Hamilton, and Waterloo, along with dedicated bus services to connect higher-order transit lines to the airports themselves. Travel time will not be instantaneous, and yes may be slower than a link to Pickering, but it will be possible.
Environmental damage will occur no matter which airport is expanded, but the Pickering Federal Lands remain untouched greenspace as of now. If the airport is cancelled and the land placed under protection, it can remain an agricultural preserve in perpetuity - all that's lacking is the political will to do so. Land around Hamilton and Waterloo airports will be lost as they are expanded, for sure, but those airports exist already, and that loss will be hugely less than building an entirely new one. With regards to fertility of the soil, the airport lands in Pickering are nearly 100% located on Class 1 soil.
And as to drawing jobs to the east of the city, it's folly to think that manufacturing and industry will suddenly experience a rennaissance in Durham if catalyzed by an airport. These sectors have been in decline not only in Durham but indeed across Ontario for years now, and the factors pushing that trend along will not easily be alleviated by an airport in Pickering. If there are to be expansions, there are serious vacancies in already industrial-zoned areas in Pickering, Ajax, Whitby, and Oshawa near established road and rail connections. No need to tear up greenspace for more.
I could drone on for days, but I'll stop now for having pulled this thread fairly off-topic. As you've said that my posts are in part just my views and not facts, so it is the same with yours. I'm not at all trying to pit the GTA against itself