It's been pretty normal for new-mid games ... forever. Mostly because even though it makes the game longer, it makes you "feel" like you aren't losing. Plus, it takes long enough to get a game as it is for now, making the game longer is more of a good thing than a bad.
Also, spirit bullshit is more common in lower-ranked games and High Towers helps a ton against a spirit oak, even if you don't know how to counter. Consider that many newb games are "rush to giants -> win" because that is how it typically works in lower level games.
Spirit Oak can't really deal with Giants, and the more time he takes tearing down your towers gives you more time to get Giants. It all makes sense (:
Also, it makes Oak/UB stronger and those are pretty damn popular demigods. Also, Reg players, still one of the most popular demigods, benefits immensely from High Towers since it helps keep his sorry ass alive. Plus, with Scope he can still take a tower down in roughly 2 hours without taking any damage (: