Exactly. Sometimes the best thing to fill up space on a map is "nothing." Just the player and some scenery.

I spent so much time in Halo CE back in the day just goofing around, seeing if I could do things like get to the bottom of the map room or security room shafts in The Silent Cartographer, or jumping the Warthog over hills in the second level, or just enjoying the scenery. Speaking of that second level, it was a marvel for its time and still holds up well. You play the first level and it's just another FPS corridor crawl. But you step outside of the escape pod in Level 2, and you see this open field in front of you. And the game lets you explore it. There's no collectibles (at least not in the original release). It's just scenery. Enemies eventually show up, and there's consistent fighting until you get the Warthog for the first time, but there's also large chunks of the level that are empty. The whole rest of the first half of the level after you fight off the enemies at that tower is just space to tool around with your new ride. Once you clear out the first half of the interior area that connects the two main outdoor areas and activate the light bridge to progress, there's no more enemies until you get to one of the three areas where you have to rescue more Marines. Sometimes that central area that joins them will have a pair of Banshees or some troops spawn in, but otherwise there's nothing. Again, just scenery.

Other levels in the game have a higher population density of enemies, but still have moments of total downtime, some of which let you appreciate just how big the world is. Honestly, just playing a level like Assault on the Control Room on foot made it feel bigger and more grand that any open-world game I've played despite being a small fraction of the size. The grandeur of those giant frozen canyons was enough to engage me without constantly pushing me to do a bunch of busy work. Also, The Silent Cartographer's interior areas have those chasms that serve no gameplay purpose, but still let players ask "Can I get down there?" And many of us spent hours trying to do just that. The game gives you downtime that exists to take a breather and soak in the world around you or to just screw around and make your own fun.

As I said, Halo Infinite could have easily told its main narrative, did its environmental storytelling and showed off its grand Forerunner buildings, given players neat little places off the beaten path to explore, and offered solid encounters with a traditional linear Halo campaign consisting of eight to ten self-contained levels. It didn't need a single gigantic overworld dotted with the same copy-and-paste busywork objectives.

As always, depth > breadth.

Luckily most games are not $100m.

Most JRPGs are massive with huge worlds and 80-100 hours of content and gameplay. You don't see any of them selling 6m these days. And yet they keep getting made, most series get multiple sequels in one generation.

TOTK had a 6 years development cycle and over 1200 credits of professional work. It's totally an AAA game, no discussion

Mario Odyssey has 290 credits. It's 40% less of Astrobot's, although it's partially because things like localization, offices, global project management, bussines operation, etc. But both games look similar in scope, but of course PS5 has better graphics because it's developed for PS5 so they probably needed more workforce to work on those models and animations. Both were developed in around 3 years. I will classify both as AAA too, but on lower-end on the budget. Maybe sub-100 million (and of course well over 100 million for both with marketing costs, which was HUGE for Odyssey, even in Brazil where Switch was not even released in 2017 there was marketing for this game) 

Xenoblade 3 has ~1k professional roles but ~130 were voice actors and ~370 musicians, singers, music producers, music production staff, etc (I asked chat GPT to count for me, so take my number with a grain of salty!). It's quite interesting how much effort and money they put on music, if you ask me it must have one of the most expensive music production among japanese games. It also features motion capture and tons of outsourcing for QA and Testing. It had a 4 years development cycle, I check all the items for AAA development in my book as well and maybe the most expensive JRPG outside Final Fantasy and maybe Dragon Quest XI? 

Metroid Prime we need to see the credits list, but it gives me strong AAA vibes. They restarted development in 2019, so its a 6 years development cycle. Given the game size, graphics and duration I will not be surprised if it's the most expensive Nintendo game yet.