Here are the current regs for elevated stands in MN.
Elevated Stands
• No person may take deer from a constructed platform or other
structure that is higher than 16 feet above the ground. This restriction
does not apply to a portable stand that is chained, belted,
clamped, or tied with rope.
• In Wildlife Management Areas and State Parks open to hunting
(see pages 76, 81, 82, 85, 119-121), only portable stands may be
used. They must not be left overnight. Portable stand use is
encouraged in State Forests (see page 128-129).
• In Scientific and Natural Areas open to hunting, no stands
(including portable stands) may be used (see pages 131-132).
• Any permanent stand on public land when not in use is considered
public and not the property of the person who constructed the
stand. Any use of threat or force against another person to gain
possession of a stand is unlawful.
I also agree that when a permanent stand becomes abandoned they can become an eye sore, with a portable you have allot more flexibility to move to a new location.