I've been watching all the ranting and raving and screaming on both sides, but this is the first time I've made my voice known outside of quiet talks with friends.
I work in promotions to clarify where I get all this from, and the first step to selling any new product is to either identify or create a need. Since RPGs are entertainment, the need must be created. While the execution left a lot to be desired, the videos and podcasts and posts that many found so offensive did a legitimate job in creating the need. The second step is minimizing backlash. Whenever a new version of an old product is released, there's backlash and most companies employ diplomatic staffers in order to deal with direct customer complaints and well-spoken wheelers and dealers to handle it in the media. WotC seems (I'm not on staff, I can not speak for their intent, only the apparent results) to have chosen the more direct method of ridiculing and silencing naysayers where they have the power. There are a lot of tiny steps in between, but the next big one is to claim success, no matter what the actual results were. I have not seen numbers, but I choose to take WotC on their word in their claims that they have outsold every other edition's initial release. In this, I applaud their marketing success. They did very well for themselves and marketing students should take a look at how a apparently poorly run campaign that stirred up controversy and vitriol on both sides can sell a lot of product.
From that standpoint, they abandoned nothing. Their only contract with fans was to put out a product. The fans take it from there.
Now, to step away from being rational and logical about all this, do I feel abandoned? No. I feel ignored, stepped on, and generally black and blue after the treatment that something I have allowed to become a large part of my life has received. While the game mechanics are not so bad, and do indeed have some things that interest me, it's the giant bleeding hole that they left of Forgotten Realms that most hurts. Then, when I yet had hope that 3rd party publishers might salve the wounds, the GSL was released. I would more generously open my arms to a rampaging owlbear than embrace 4E at this point, and while I'm sure that I'll eventually get over it, not yet.
For everyone that is playing and looking forward to playing 4E, I wish you the best of luck and lots of enjoyment in your future games.