You have a very short memory. Google has NOT always integrated sign-ons between those services, and there was an uproar when it happened.

You are right -- I don't really remember when I had to login with different credentials for Youtube, et al.

Just to clarify, I am making a distinction between being able to sign into a Youtube profile with a Google account and forcing the same profile across all Google properties.

Judging from my preferences, and based on my (limited) anecdotes, it seems that users appreciate the convenience of single-signin solutions, as long as each property they are signing into has a profile that can be managed separately.

If you seriously don't want to, just create two Google accounts...I'm using multiple sign-in across many of their web properties with my personal account and my corporate Google Apps account.