I hardly find "why" an inappropriate question, and in fact it's posed as the topic of this thread. Do you like Jock Sturges for his platinum printing, for the clarity of his sight, or because young girls are beautiful? All might be valid answers, and may or may not be contrary to one another.
In fact I find "why" a far more interesting question than "what." Personally, I've never been all that impressed with Adams, and yes, the reasons for his popularity elude me, especially when so many of his f/64-era compatriots have faded into obscurity. The only answer I can come up with is the comfortable safeness of his idealized imagery, which does indeed sell calendars and puts him in good company with perennials like Kinkade and Norman Rockwell (to say nothing of Anne Geddes). YMMV.