It is understood by a large number of people who cannot read the Urdu script. To have the poems in Urdu script would have meant depriving all these people of the richness and beauty of Urdu poetry. Transliterated Urdu, or Romanized Urdu as it is sometimes called, is the only way to reach the largest possible audience. Where there is no possibility of confusion, the underscore may or may not be included for compound words. Two consonants will always be separated by a vowel sound.
Some words have the two or more consonants merged together.
In such cases, the consonants are written without a vowel sound separating them.