Why does that bug you? Zhaitan was a stone's throw from the Grove based on the map layout.
The tower only recently formed when Mordremoth awoke (as in within months/year of Scarlet, remember that he wasn't active until only recently). Zhaitan's awakening ushered up an entire continent, Mordremoth erected a tree (Scarlet grew a corrupted Pale Tree in a few months, remember, so his offshoots grow fast and reached all the way to the Shiverpeaks during Season 2). Tarir was dormant, and just a relic covered in foliage and is actually below the canopy of the jungle, and Novus is completely buried, isn't it? We're seeing the bottom half of it in TD, the rest is under the jungle and the top half is lost
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None of this is all that farfetched. Their only big "flubb" for story/layout was Novus in general just being introduced out of nowhere. Even the "dragon weakness" malarky was more or less built up with Zhaitan, who's weakness was exploited (rob him of his minions, eyes, and mouth. He was overly dependent on his plague-like minions.).
Also "lanes" is perfectly standard for army movement in large columns, which is what's happening on DS. Mordremoth has little choice but to muster his forces in a similar defense, and the back-end of the Pact base is guarded by the Krait Orb preventing his minion's passage and a pincer. Its actually pretty well planned out for what it is.
I have my qualms with the expansion and ANets focus on bleeding money from its consumers with gemstore bullshit, but I am a big fan of their updated story telling, map design, and map event chaining. Its much more interesting to go to those maps (also the gliding stuff is spot-on) and partake in map wide efforts with a common end goal. The old maps were, sadly, basically barren to anything but map completion, leveling up, and farming trees/ore or bosses. Empty, dead maps for the most part. No matter how that is handled, it would always result in taxi wars 2.