By reading with Tajweed you ….
The second reason is that you will be …
2. Fulfilling a Divine Command: Allah commands: “And recite the Qur’an with measured recitation (tartīl).” (Qur’an 73:4) Tajwīd is the practical implementation of tartīl. Reading without regard for Tajwīd contradicts this command, even if unintentionally.