Okay, so we're playing it smug, I guess:
I don't know if anyone has told you, but there's this thing called solar gain that actually keeps a building heated at night when it's been absorbing sunlight all day. To your second point in this paragraph, outside temp knocking at a window means something very different than letting the sun through technologically evolved glass, regardless of time of year.
I don't know if anyone has told you about temperature regulation systems in buildings. Anyway, designers of libraries (hell, buildings) have this concept mastered.
Simplified vertical Circulation. Public communal space... many large libraries adhere to this typology for a reason (the building becomes a room in the city, which it could not otherwise be given its urban context). Easily apprehendable wayfinding (Libraries rely heavily on the ease of this, it's basically the most important thing), Easily apprehendable classification system (areas/floors devoted to subjects). It's easy for a family to come to a building like this and separate to areas of their specific interest (on different floors even) and still keep tabs on one-another. Speaking of families...kids love spaces like this, and its important to target that in a library of all things. Precedent: look at pictures of old libraries...this space plays on that tradition.
I suppose I could go on, but I've already met my own standard. To boot, this was approved by people who have a much better idea of what a library needs to be than you likely do, and built by people who likely have a better idea of the cost vs. benefit calculation than you do...your attitude seems to take the position that this was designed in a vacuum, or worse, that technical details simply trump socio-cultural considerations in building design. This is the difference between architecture and engineering, and the reason we have both.
Source: am architect