Sonic Team's integration of Pictochat-esque chat in Zero is a small stroke of genius that plays wonderfully on the strengths of the DS, will break down linguistic barriers, and is a wholly original approach that would only be possible on Ninty's system. While I'm expecting to see plenty of vulgar images crudely scribbled by pubescent idiots, I still believe visual chat will provide players with some awesomely fun and creative opportunities.
For a start, whatever doodles appear on my DS's screens, I doubt anything will be as offensive as the juvenile blather you'd have to put up with during a typical hour on Xbox Live. Sexism, racism, homophobia: all of these are dishearteningly common on Microsoft's service, so perhaps a less speedy form of communicating would help to discourage the morons. Because seriously, who needs this in their life?
Speaking of speed, while voice chat might be the best option for fast-moving games, where issuing warnings can save a team-mate's virtual life, Phantasy Star games have never required lightning reflexes. Text chat was perfectly adequate on the Dreamcast, and it will be perfectly adequate here.
Visual chat also promises to be a heck of a lot more stable. As a regular online player of Advance Wars: Days of Ruin, I'm constantly disappointed by the voice chat function. Being in the UK, my conversations (particularly with those in different continents) are often fractured or break down entirely, and the sound quality is hardly the best; even through headphones, my opponent's voice comes through as a barely audible murmur. Phantasy Star Zero's visual chat will mean your message is more likely to get through, and it'll be a lot easier to understand.
On top of that, it should ensure everybody gets heard. I don't know about you, but the idea of playing alongside three allies who repeatedly speak over one another is hardly my idea of fun. By allocating an equal amount of space for the (drawn) thoughts of all four players, Phantasy Star Zero is far more democratic than many other online games. It's a space where shy, quieter people can express their views without being shouted down by boorish, self-important types.
Also, I draw awesome Rappies, if I do say so myself.