It is not that developers arent curious. They probably are in their cages set by bad project managers who dont even play own game and dont notice it takes forever to load.
The project managers could put load times as a priority but they genuinely dont see it as a problem or dont care at all.
It happens all the time. There is a lot of unoptimized software.
Perhaps the issue comes from the top: the project managers are supposed to only do things that increase revenue and all other things are not rewarded at all? Perhaps executives only care if they hit quartely results? (Short term gain traded for long term loss - the game is made for whales who are so invested that they will play even when it is technically bad - so milk them now with new content for whales and ignore everththing else, who cares that new players will be discouraged by bad load times).
In my opinion if nobody plays own game / eats own dogfood, they dont even see its problems. Blizzard is at this stage now - some of their games barely work. You buy Starcraft 1 through the launcher... and it doesnt work(I think it works now, but it took them 1 month to notice it and another to fix it). Heroes of the storm - downloaded a 137mb patch every run - it took them half a year to notice it and do something with it. It is like nobody cares about the brand at all. Game company where your games dont work.
IMHO a problem with people - that comes from the top. They want only story points for things that bring money. The project managers either dont care, or cannot deal with other problems at all. I bet they dont care. This happens in many companies - there were few people who tried, they got burned for that: terminated or quit -> so now nobody cares. "The game is good enough to still sell some skins to the whales, so why bother".
Look at the results: they got an external comment what to fix. Did they launch their own internal project to optimize the game? Did they check for other things that make it load slow? It looka that someone else did a partial fix that is "good enough" so everything is back to usual and nobody cares about load times.