What is the benefit of a pasta pot with an inset?
I find these gadgets inconvenient, so, I would say no real advantage.  I cook pasta in a large stock pot, and remove with a spider to the pan with the condiments. I can even cook several batches in a row this way. I don't really find inserts helpful, and don't need the extra "stuff" in my cabinets. Your point about extra expense, space, and clean up is accurate. I will also add that the insert takes up significant volume in the pot, so you actually lose usable space.  They are just not necessary.  Spend your money on a good, solid, multi-purpose stock pot.