I know not following Makharij in Quran recitation changes the meaning. But, is Madd, Gunnah in Tajweed for beautification of Quran recitation only?? Or it changes the meaning also in arabic not following those rules?? As far as I know tajweed is not followed in regular Arabic conversation.
As you mentioned Quran is not read like Arabs speak in Arabic. Quran absolutely has rules how to recite it and it is called 'Tajweed'. One must recite Quran following the rules of Tajweed. It makes your recitation more beautiful. If you don't recite it without Tajweed it's meaning might change. Allah says in the Quran,
"Or add to it, and recite the Qur'an with measured recitation."(73:4) Allah commanded you to recite Quran following the rules whether it changes the meaning or not. Quran is not like a normal book. It is sent by Allah and it must be recited in the way Allah said.