I don't think it has anything to do with market share, the iOS betas attract more users because they offer more attractive new features. For better or worse, iOS 7 was a huge redesign and many people wanted their phone to look "cool" early.

Trying to explain to non-techies why Mavericks is better is much harder, aside from better battery life.

For me, the standout feature in Mavericks is the "Ram Doubler" feature (for the old fogies among us who even remember what Ram Doubler was) -- lets you get away with having less RAM.

Given that Apple now solders the RAM and charges relatively high prices for it, the memory compression is a pretty nice feature to have.

And here I thought I was the only one in these parts old enough to remember Ram Doubler, which I do, fondly.

Although not RAM, but shows my age, how about Stacker?? (HD compression when I had a 20mb HD)

I was such a happy camper when the Mac version of Stacker came out. That was the one thing I envied about my DOS friends.