The problem is that you can lead them only on a path if you offer them a straight way to you. And then you have only 4 Choices
1: You need to defend in Meleerange (= you dont fight the next wave and so this wave will kill you)
2: You abandon the base and drive the rest of the night
3: You make a fall hole and send them again on the same path
4: You setup at the end of the path a trap that make so much damage that nothing will survive it
(3+ Bladetraps + E fence + maybe turrets or mines)
If we can arrange us that option 1 make no sense and 2 is equal cheesy as 3
Then we need only to talk about 4. And theres a simple question, why is a fallhole (what would be in real a 180 Degree turned hatch with a spring) more cheesy than a bladetrap ?
And finally the answer (in my opinion) is that the only difference is that repairing blades, fill turrets and replace spikes is simply more expensive and timeconsuming than repairing the Fallhole blocks.