Fine but whathappens when...
1) Some idiot with a JCB (backhoe) digs up your business critical network link and it is down for several days?
2) When the cloud hosting company has a snafu in their billing system and cuts you off from your business IT systems?
IMHO, these alone makes using something like Azure or S3 incredibly dangerous to a business if you don't have a 'plan b'.
The same goes for using server hosting companies for this stuff as well.
IMHO, put your web frontend out there in the cloud but do you really want all your critical systems exposed like this? After all, if these are down/unreadable your business could go down the tubes.