Every landing I've made in A320 was with engines at idle, incidentally A320 is swept wing jet.
Every landing I've made in Q400 was with engines above idle, incidentally Q400 is straight wing turboprop.
As it seems to be type specific ant generally not related to wing planform, what is your definition of "idle landing" anyway?
all airplanes at 1,3 Vs have the same manoeuvre capacity
Maneuver capacity is not limited to capability to pull 1.69G before stalling. E.G. Lockheed F-104 has a bit bigger 1.3Vs compared to Cessna 150 and therefore somewhat larger turn radius at that speed.
Since wings were swept to permit higher and faster flight, what are the disadvantages they have when flying low and slow?
You've already mentioned primary disadvantage: