It would be nice if Mac Walters and Co. released audio commentary that walked through the entire ending sequence. Just to paint a picture of what they wanted players to see or "speculate" about during each key moment.
Looking at those pictures from the 'final hours' and the art book, I think you'ld be very dissapointed by what they would have to say. Also, it's usually just making up stuff anyway. It was cool when Starbreeze did, sorta worked in the Half-Life episodes, but anywhere it's just.. not really something you would look for, I guess.
That said, the Babylon 5 (tv show) commentaries are pretty awesome. "that doesn't just look like a toiletseat".
SPECULATION TIME:
Btw, from the "I hate developers" topic I have gotten the idea that preparing marketing assets is also a lengthy and troublesome process, so there are a few things worth considering:
(from the final hours

about 12 months ago, the ending wasn't fixed yet, but there was a delay and then the 'CAT' mission (the prothean) was cut and moved to DLC. The 'CAT' is known from the leak to be 'catalyst', which the prothean then was for some reason. (unknown why or how)
from the art book and the final hours, we know that TIM used to be a bossfight, but was moved to be less 'videogamey' (their words) and not have him suddenly change into something completely different. This does make sense, but it gave us the weird TIM confrontation.
If we assume an ordinary publishing routine for the various marketing assets, like the art book and (unfortunately) the last novel Deception, then the process would have started at least six or nine months ago, but more likely even further back, about the same time they changed the story sequence. Whether this changed Deception is hard to say, but I expect it did.
(since both CAT and TIM were changed by then, meaning that the story would have been very different between the pre-delay and post-delay fase. kai Leng probably got a bigger role as well, as every other novel character appears and dissapears within one level, yet Kai Leng does not)
Keeping those timed events in mind, it's not entirely unthinkable that the current ending was a rather hasty 'crunch time' solution to a lack of time. The fact that the Prothean was also moved from being 'post release DLC' to 'day one DLC' also supports the idea that the publisher was getting impatient / moving up the timescale.
Probably just stating the obvious speculations here, but just thought it might make thing a bit more understandable from our perspective. Until an actual post-mortem shows up, that is.