Probably because fuel is so much more expensive than electricity.
You avoid having to climb all the way up just so you're using up less of this very expensive fuel, which especially on short haul flights is a huge % of the whole flight.
Not actually economical in terms of energy used per distance covered, but more practical and likely to be appreciated by passengers? Less stress on the airframe too, probably.
Noise could be an issue too— no one wants a passenger jet flying over their city at <5000ft, but maybe it wouldn't such a big issue if it was a lot quieter.
You avoid having to climb all the way up just so you're using up less of this very expensive fuel, which especially on short haul flights is a huge % of the whole flight.
Not actually economical in terms of energy used per distance covered, but more practical and likely to be appreciated by passengers? Less stress on the airframe too, probably.