What's the biggest challenge to overcome when facing a turtling team? A: A lot of sentries. But not just any design of sentry location. When you have 6 or so sentries grouped together, a single demoman uber can take them all out. When, as in Hydro's "Dam" point, its "Bridge" point, and its " Satellite dish" point, or in dustbowl 2-2, there is enough space to spread the sentries out in a pattern that covers each one, stalemates arise because it is nearly impossible to overcome the knockback to destroy all the sentries. Now look how the intel rooms were designed in Meridian. Sub: Tight area around the intel, lots of entry points though. Temple: Same. Village: Same, especially on Volcano-Village. Boat: Same. Volcano: A different challenge for both defenders and attackers, because it is at once the largest and most open area. Now that the windows on the intel room are removed, there is no one effective sentry location. Defense has to get creative to turtle on this one, especially as a single sticky jump can get the flag carrier up and out of the base.
Red's lair is pretty balanced as far as wins/losses go. However, it is definitely the most effectively turtled- but hell, taking the last point in a TC map should be difficult anyway.
We're not ignoring your criticisms out of ignorance, rather sticking to intentional design that has proved itself in playtesting.
By the way, Shmitz or I usually lead our teams to victory when playing. Coincidence? No, we know how the map works. Strategy IS needed. So no, bumrushing into the base without a plan will get you nothing. Getting an uber in there, hitting the sentries while a spy helps you, having a heavy cover the spawn exits and allowing your scout to jump in there to grab the intel will result in a successful capture. At least, so says 132 rounds of playtesting.