Why Tajweed is necessary to learn & Why to apply it while reading

Tajweed Meaning is not about the melody of the recital. It is about accurate pronunciation. You can read the Quran with tajweed (i.e., pronounce the words correctly) with or without melody, and it would still be correct.

Tajweed is only needed for reading the Qur'an, Tajweed, as is explained in all tajweed books, is the art of keeping your tongue from performing a mistake in the recitation of Allah's word/ The Quran.

Tajweed adds a beautiful voice, but that is not only, but it also helps you keep from making recitation mistakes. Allah states in Surat 73 Ayah four.

There are three kinds of "reading" in the Quran; "telavat," "qurae," and "tarteel." Telavat is reading a text usually. Qurae is reading it, presenting your mind entirely, and trying to learn it. Tarteel is reading a text word-by-word, thinking on each word for a long time, maybe for some minutes. In this ayat, tarteel is used. The bold part of the ayat is translated as " And tarteel it with a tarteel."

As you understand, this ayat has no order of reading the Quran in an ideal way with melody. In my opinion, some people love to hear the melody, and they want to read Quran with melody too.

They think it would be great if they read Quran with melody. But there is no order in the Quran to read it with melody. First of all, our primary example must be the Rasul Allah  Muhammad (PBUH); he never read or made people read Quran with a melody in his entire life. 

Artistically reading the Quran is just a bidat that is made to Islam with some melody-loving people (I'm not saying that loving melody is terrible. It is a different subject).

Allah wants us to read the Quran, know it, and live according to it. Allah and His Rasool do not command us to use Quran as an art tool.

The people who insist that Allah orders us to read Quran with tajwid also claim that Tajweed is needed for understanding the Quran correctly.

Their famous example is the similarity between the reading of the words "helek (to lose a life, to be wasted)," "Halak (to shave)," "khalak (to create)."

They state that, if non-Arabic readers don't read Quran according to Tajweed rules, they misread words like these, and they misread the whole Quran at all.

They are already not understanding a word they read. What is the importance of accurately reading a text that you don't understand? The readers that know Arabic are already know how to read, and they are correctly interpreting the Quran.