It is not just you. I have no inside info, but my guess would be that it comes down to money and licensing. 5e is where development and sales are for WotC. I would think that they would be loath to develop anything for previous versions of the game. Not only would it dilute their brand, it would lead to consumer confusion, and cut into resources (talent, marketing, etc.) better directed toward their living product. As such, it's also unlikely they would license previous adventures. As for a Compendium, that's more difficult to speculate on. It could be something as complex as a licensing deal that forbids development of such (for reasons above), or just a general lack of interest in doing so in favor of developing newer directions. Again, all of this is wild speculation on my part. In any case, you aren't missing anything. The offerings of anything for previous editions of D&D are pretty sparse.