I thought the same thing until I wore big flat spots
in 2 tires. It happens as you enter or leave gas stations.
Tow vehicle rear wheels drop into the low drainage
area at the curb, trailer wheel contacts pavement,
can't swivel because we pulled it all the way up and
locked it. BTW, I'm convinced this is the scenario
that over-stresses your trailer tongue and leads to
failure.
JJ

At 20:00 11 January 2005, wrote:
I think removing, carrying and reinstalling the jack
is too much
hassle.
I thread a chain through the jack's wheel housing and
attach both ends
via a climber's snap clamp to the trailer's tow bar.
Takes about 20
seconds.
Bela