The conventional wisdom regarding Ecclesiastical Latin pronunciation is that it does not feature the vowel length distinction we find in Classical Latin. This is a misconception. If you open a Catholic hymnal, you'll find it full of Classical meters whose beauty as poetry is largely based on the correct pronunciation of vowels.
If you prayed your breviary yesterday, you chanted a nice Sapphic stanza at Matins with "Virginis Proles" and iambics at every other minor and major hour. The liturgical calendar is getting close to the end, so we'll be replacing the "Salve Regina" with the dactylic hexameter "Alma Redemptoris Mater" for a month or two in the near future.
There are some who will argue that most ecclesiastical speakers and writers both contemporary and past do not actually pronounce or even know the proper vowel lengths of words, and that therefore Ecclesiastical Latin does not use vowel length, but this argument is flawed. If we judge the features of Latin based on the practice of cherry-picked speakers who either don't know better or don't care, we would be forced to conclude that also Classical Latin has no distinction of vowel length. This is an absurd conclusion, and the logic flows in both directions.
If you speak or read Church Latin, learn your vowel lengths, so that you can appreciate the vast treasury of Latin poetry used in worship to its most full extent.