A bigger plaza around the library sounds nice in theory, but I'm glad they didn't got for it as I think it would've ended up being an empty wasteland. Apart from the library itself, what exactly would be the draw to hang out at that location? Every successful plaza has a perimeter of things that people are drawn to...shops, amenities, architecture, art/cultural institutions, etc. As things stand, the library is facing the ass-end of city hall, a senior's residence, the Salvation Army, and is book-ended (heyooo) by two parking garages. Exciting stuff.
That, and there's already a plaza a block away in Olympic Plaza, that already looks to serve the same purpose. Instead of trying to make one great plaza, you'd probably have two mediocre ones.
The library that we did end up with already has a decent enough outdoor public space, and it's not exactly bustling out there (at least not with the demographic one typically hopes for).