Actually, I think its syntax isn't just simple, it's simplistic. It's simple to implement, but it presents some rather unexpected behaviour to the user. To wit:

  proc hello {} {
    # I'd like to put an unmatched { in my comment
    puts "Hello!"
  }

This doesn't compile because of the unmatched {.

But this does, by adding another unmatched } - in the following string:

  proc hello {} {
    # I'd like to put an unmatched { in my comment
    puts "Hello!}"
  }

In other news, Richard P. Gabriel can stop arguing with himself about whether worse is better. In this case, worse is pretty silly!