I agree; in fact, there are passages in which God tells us to be "crafty" like the serpent and "the serpent was the most beautiful of all creatures".....He did a great job creating them! In terms of persuading your audience to like large snakes from an environmental standpoint, they are valuable in many ways:
1) in some countries they provide a source of revenue for local tribe people who sell their skins to make a living (not exactly something we snake lovers enjoy but it is an important part of certain cultures
2) in some cultures, particularly south american indians, large constrictors like the anaconda are worshipped and play an integral role in these peoples' lives
3) large constrictors help cull large mammal populations.
4) large constrictors are an important food source for MANY animals...that is, baby boas and pythons are food for many mammals, birds and other reptiles
5) these animals are just one small part of a much larger biodiverse picture that is a part of our natural history and as such, needs our protection.
There are many more reasons but hopefully this will help your cause. Rob
Rob Carmichael, Curator
The Wildlife Discovery Center at Elawa Farm
City of Lake Forest Parks & Recreation (IL)