I'm cool with con exclusive content. It's a perk for those dedicated enough to find the time and money to attend the convention. It's a nice something special. However, I prefer it when it's something like a repainted miniature, an alternate cover, some dice, or something else that's a small bonus or otherwise attainable elsewhere.
This is not that.
This is very much not that.
Okay, if it were just the core rules being cheaply published as a softcover rulebook playtest, that would be fine. I did a post on this a while back advocating a finalizing of the form and focus on fine tuning over heavy revison. This is a good thing, especially if we can continue to get the playtest information as a slightly less pretty PDF. No big deal.
But adventures?! Content for the actual game. No. I'm sorry but that's unfair. The proportion of people in the hobby able to make it to GenCon is a huge, huge minority. If 1% of D&D players gets out to GenCon each year I would be incredibly surprised.
I love GenCon and plan to go next year but cannot afford to go every year.
And this is not a cheap hobby. Plus there are many collector geeks out there who want everything. Geeks tend to be obsessive that way. WotC seems dead set on making it hard to be a D&D completist. They don't re-release Encounters, they don't reliably make their free RPG day content available, they've released exclusive stuff to the RPGA, and more.
Especially when they announce this so far in advance.
All this does is encourage non-D&D players to get the product so they can sell it on eBay or elsewhere.