Separate file systems / volumes / partitions for the OS?

I was wondering what folks are doing these days as far as creating separate file systems (volumes,partitions)? In the past I typically like to separate out:

/
/var
/usr
/home
/opt
/tmp
/boot

Into separate LVM volumes and file systems on say a RHEL6 system.

The arguments for doing this:
1. filling up /var, /tmp, /home still doesn't fill up your root partition /
2. ease of monitoring / diagnosing full file systems
3. duration of fsck is generally faster on smaller file systems
4. security, you could make /usr ro in theory

I'm thinking about this in context of a virtual machine of some sort.

In general it seems like doing this is more trouble than its worth these days, especially with cloud type deployments. Most cloud providers seem to give you a straight up "/" and that is it for the OS. If you want a scheme with separate volumes like above it can be done, but you generally have to jump through a bunch of hoops either importing images into the cloud or doing surgery on their images.

In general I'd like to stay away from customizing OS cloud images as much as possible and use the cloud provided image and apply customization on top of that. The more VM / Cloud solutions one uses the more one spends their time updating images.

So I guess I'm looking for what folks think is "best practice" these days. I'm leaning toward living with one big root partition for the OS.

Thanks!