You are confusing a few things: anonymity (taking actions that have no authors) is not pseudonymity (using a persona); being accountable and having several facets is yet another distinction.
Anonymity prevents coherence, accountability, structured organisation, but it can make great things: voting by ballot is anonymous, or Anonymous, the headless movement. Google refuses those entirely; any service that has moderation needs accounts, and temporary email accounts were used to re-introduce anonymity. By fusing all your accounts into a single, coherent entity, Google allows basic facet management, and reduces commonality to name and avatar... but those are the most commonly representative elements of facets.
I still thing "troll" is a made-up category that prevents proper understanding of on-line etchnography, but, to answer to Liz, trolling is not done by "anonymous" (you can point at "the troll"), but it is often done by pseudonymous users; users who sign their civil name and have an articulated presence on-line can be called trolls (I've had, many times).
As my second favorite blogger (after Marshall, a French barrister who explains how law is actually enforced) is pseudonimous, and cannot reveal his identity (so that he can leapfrog the attorney-client secrecy and explain representative cases in details), I'm glad that Google would accept him under his nom-de-plume, de facto his real name (no one cares about his civil name) -- however, I'm ambivalent about their rule: would a fellow barrister of his be able to start a G+ based blog?
With different facets, you can offer incoherent messages (preaching against sodomy and having bathroom encounters) to escape accountability between the two, but in general a pseudonym is a brand, however narrow, that commands local coherence. "Liz" is a good example of that: I haven't searched for all the information Google could give me about you (none to be honnest): I have a handle for you, "Liz" (and "BabyYeah72CA" would be fine for that, although unlikely among Marshall's reader) and I look for internal consistency, rather than long-term accountability. I could make inferences, like "(Awesome) Quilty" sounds suspiciously pseudonimous, so you might want to defend.
From experience, letting people be female on WoW, or gay away from the spotlight, or an asshole to fellow token-conversation partners on-line to relieve their need to be admired rather than share their opinion; any change in persona, is a good thing -- as long as the people arround them you accept the inconsistency as part of a process to acquire perspective. Don't call someone a troll, or accuse them of being "a fat, perverted, hairy bastard with odd fantasies of having surreal boobs": ask them why their changed, what they learned not being nice, or 'themselves'. Judgement will come soon enough, but it won't be fair until you established a rapport with both personna.
It's hard for someone being bullied to make sense of anonymous violence, but taking it as a massive call for help, a reaction to unexplicable discomfort is the only way to make it bearable. Formal pseudonimity allows one to mark a needed distinction between the two.
Therefore I think Google+ is designed for mature identities, but allows little pseudonimous emergence and hardly any exploration via identifiability-proof persona, two essential aspects of personality building.