A huge giant. Head above the clouds and terrible HUGE bulking arms wielding
axes of detruction and carnage! Little birds flee, humans scream in terror
when this horror approaches. Then this terrifying giant sees a tiny door which
has a very tiny lock. "God damn", it thinks. "I cannot bash this door down",
it says and goes away.

An intelligent mage. The knowledge and power to kill a dragon. The willpower
to destroy the whole villages.People fall down on their knees to worship this
deadly and beatiful sight. Then this mage sees a wooden door with a metal
lock. "God damn", he thinks. "Despite of my all great powers, its impossible
for me to melt this door or the lock." He sniffs sadly and goes home.

Right. I know it would be too suffeli+ to cast lavablast and melt the door or
the gate down. Or cast psicrush to shatter the door into the zillion pieces.
Or use your horrible strenght just to bash that door down. Or would it?

Yeah, instead of going and killing big monsters to get keys, we should be able
to call the LA police and have them Rodney King a Door until it breaks. While
everyone agrees that destruction is destruction (via it a monster or a door),
it's just not practical to do it that way for obvious reasons. I'm sure if it
helps you to sleep at night, you can consider the doors to be MAGICAL doors
that completely resist any damage!