For security reasons. Implementing a SSL layer in cloud can help us avoid unauthorized access to our resources on cloud. It secures data while it's being transferred between servers or accessed by authorized users. And SSL is not just applicable to cloud - it's applicable to any model where you do not want unauthorized users to access your resources.

e.g. by default, all communication with SQL Azure is SSL encrypted.

is there any drawback of this????

not considering the develop/architect/installation cost - I know in SQL Azure when the data is encrypted while being transmitted - it raises performance issues. Is that a problem? No, not always because the significance of performance impact can only be addressed by benchmarking the performance.

I cannot think of other disadvantages off the top of my head - but I guess a quick search should point you to whitepapers/blogs that delve deeper. Hope this helps.