I think Starfield should be considered an open-world game but we have to understand that, what gives it that open-world particularity are the 1000 visitable planets, so I also think it is correct to say that the way it creates "limited" portions of terrain and POIs on the planets, affects considerably what should be a playable open-world game.
The other day I read a player saying that the POIs created have no coherence with each other, and of course they have no coherence with what appears in other POIs nearby, obviously because there is a clear struggle between trying to script them and give them a sense of plot, and the fact that they are created randomly/procedurally.
For example, he commented that he landed on a random spot on a planet, and this created 3 POIs in one of those portions of land (of a size that, remember, can be run through in 10 minutes); in the first one some NPCs were trying to survive with hardly any food or resources, dying of starvation. Near them there was an abandoned location with some pirates, and near both places there was a military outpost... Argumentatively it does not make any sense those 3 POIs so close; the first ones should not be starving having resources so close (especially logic invites to think that they should receive help from the military) and the pirates (who were 4 or 5) should not be so quiet doing their misdeeds having a military post nearby.
In addition, he took his ship and created another landing point practically next to the previous POI, and this time the game created 1 Industrial Outpost and 1 Civilian Outpost... obviously totally unrelated to the POIs generated just a few kilometers away. Of course, those 2 portions of land so close and inconsistent with each other were really completely isolated, by the invisible barriers and by their own nature at the time of creation. So close and so far away at the same time, hehehehehehehehehe.
An open-world based on clicks and loading screens, in separate portions with invisible walls... ok, it's open-world, but with some unpleasant limitations that almost break that feature. I don't think any of us (from this Space Sim forum) were thinking precisely about this when a couple of years ago we were impatiently waiting for this Starfield and the "1000 planets exploration", even though we knew it was mainly an RPG.
And this is not a criticism of the game, it is simply to demonstrate the limitation of the method chosen by Bethesda to deal with everything that has to do with planetary exploration and the creation of POIs (with a brief own storyline). It has its very good things, and its not so good things. But it certainly clashes head-on with the open-world concept, and also in part with being an RPG (because of the inconsistency between POIs).
On the other hand, it really worries me (as with all Bethesda games by the way) that we have not even 1 week with the game and people already "trust" that part of its deficiencies, and/or the personal playable desires of each one, will be achievable thanks to mods.
It doesn't seem coherent to me that we consider that the game "meets the expectations" if we have to leave its "polishing" at a playable level in the hands of external mods from the first week of live...; first of all, I don't think that will be of any use to console players (or, in the best case scenario, they will have to wait to see if Bethesda releases a package for consoles with the best mods made for free by modders..., and if they do, it will be years away for sure). Secondly, and speaking as a player who invested hundreds of hours in putting mods to Skyrim, under my personal experience these mods really end up transforming the game so much that it ends up being just a shadow of what it was at the beginning, and its original playable experience is almost completely diluted. That, if we refer to the base game, is not especially something to praise.
In any case, we must celebrate that Starfield is a complete and finished game, with its good and bad things, but complete and finished. And it really is very enjoyable and has some really unique things. Every complete and finished game that is released is a playable option that all of us who love this world of videogames should celebrate.