Trick-or-treating -- how old is too old?

My daughter will be 12 in December and is in 6th grade, which in her
school is the second year of middle school. I let her trick-or-treat
last year but feel like this year she has crossed into the "too old"
zone. She's accused me of trying to take away her childhood (!), so I
thought I'd raise the question here.

What do parents here think? How old is too old to trick-or-treat? When
I was growing up, 6th grade was my last year, but junior high started
in 7th. Am I being reasonable stopping her at this age, do I give her
one last year, or do folks here think trick or treating should continue
into the teens?

Thanks for any insight.

beeswing