This is largely due to my ignorance of how space travel actually works, but why can't you descend gradually (or more gradually than we already do)? Wouldn't that reduce the overall maximum heat that the craft is exposed to?
It all comes down to available fuel. Spacecraft burn most of their fuel getting into orbit, meaning that they usually have just enough left to drop their orbit into the atmosphere, where aerodynamic drag takes over. To descend gradually, you would need to have just as much (if not more) fuel as required to get into orbit in the first place, since you would have to slow down a LOT more than currently feasible. And after that you would need even more fuel to control your descent rate, since even if you stopped on a dime, gravity is going to accelerate you back to the point where thermal protection is required.
For reference, Joe Kittinger jumped from a balloon somewhere in the 100,000 foot (18.9 mile) range. The air is pretty thin up there, but he was into the thicker part before his velocity got too high. A spacecraft coming from, say, 190 miles has 10x farther to accelerate before the air becomes thick enough to act upon it. 190 miles is a long way, and even discounting the 19 miles from the balloon, that's still another 172 miles. By the time you get to where drag is a factor, you would be travelling upwards of 5,200mph (just under mach 16 at sea level). And that's just your vertical velocity assuming you managed to somehow bleed off ALL of your orbital velocity. So you would still need either thermal protection, or a lot more fuel to keep your descent rate below suicidal velocities.