I gave the OP the respect every poster deserves and read it twice and thought carefully before posting since it was a huge well thought out post. I even gave it several hours of thought while doing other things and took everything the OP said with a neutral approach. Yes placeholders are common practice, putting things of that quality in those in placeholders while in development however is not. They made a concerted effort to not only create and block entrances to this stuff but add fleshed out map geometry textures much of it custom by the looks of it. They only seem to be missing easily placed assets like kill zones and enemy spawners and possibly spawn triggers and handlers though the latter is harder to tell without seeing the guts of this thing. It may all be placed and have no triggers or handlers so nothing spawns or reacts. The point is that they put a lot of work into that when it could have been put aside for later. Also I have been a wow player for years and yes I know exactly what it's like to download huge files but let me ask you something at the 5 year point. How large do you think there will be? I know from wow it's a 9 year old game and It's got well over 50 gigs of overall drive use. It's huge and if this game will end up being that old than this is inevitable. Excluding this and adding it with the DLC will be a drop in the bucket compared to the overall file size. So yes it would have been better to leave those assets on a drive to be fleshed out later and divert them to bringing the overall quality of the campaign objectives up. Though this also depends on how many devs were on the task of adding the placeholders and it's content. But at the end of the day people looked this over and thought "yeah all those ghost objectives oughta be good enough" Lastly, it's true we don't have any direct view into how they developed things but you can get a surprisingly fair insight into it by looking at the final product under the microscope. Games like Too Human, Halo 2, WoW are prefect examples having leftovers from development that cause unique quirks or just exist with no context.