I do not utterly despise Oblivion, i actually appreciate it for what it is, but i have a few problems with OP's comments.
A main story with an intro that is very long and doesn't establish more story-important plotlines without any more elaboration beyond "the player needs to save the world" with very few nuances at all that are few and far between. It makes for an experience that is very boring and is most likely being completed for those who want to 100% the game, or for those who are genuinely interested in the story and end up being disappointed. Morrowind did a lot more with a lot little when it came to its plot, and Skyrim at least had the decency as to not present events they're not capable of showing in their buggy engine that'll end up falling flat.
And I do not think the main story is to be excused as a "small issue" because it's on you from the end of the tutorial since Uriel Septim gives you his amulet before dying, despite the fact that the player could've easily saved him and it robs the scene of any intensity when the player is purposely forced to not save nor accelerate the death of Uriel, like what if the player was allowed to kill Uriel from the beginning and then be able to join the mythic dawn the same way as Skyrim's civil questlines did. as that would make the choices you make in an RPG much more impactful, and the amount of urgency in an OPEN-WORLD game that strongly encourages you to ignore the main story and wander-off is also very off-putting, and i would say the Intro even discourages mage players since you are only given a basic flame spell, and a basic healing spell, and a bunch of scrolls (which are a one-time use only, so it's useless). and further pushes the players to get a melee class since they are given a variety of swords and shields.
About the gameplay, it had the same problems as the rest of the other games. The melee combat is strongly lacking and floaty, and given how Weapon classes (Maces, Swords etc) are purely cosmetic and aren't given any strong and weighty animations, especially to the enemies who seem to just not react accordingly to heavy/light attacks which removes the intensity of an actual fight. Granted, this was worse in Skyrim, because they added regenerated HP which further decreased the fun in combat and made it more dull and bland, since you're never really likely to die as long as you aren't stupid and aren't standing still and making the enemies pick-away at your health, but even in Oblivion, casting and swinging aren't fun as it is could be and no amount of mods could save it, which makes me want to talk about the Mods you mentioned and mentioned a couple times in this thread already.
as much as i enjoy mods, I REALLY don't like the impression it left on the community, since the community seems to enjoy and care more for the games than Bethesda does (at least on the part of polish).
it has made it so that anything that is mildly flawed in bethesda's games that is met with criticism, is responded with the sentiment "Mods will fix it!" or "Oh, yeah [insert mod name] fixes that." etc, and I really feel like people use that as an excuse that these games are less of an RPG and are more modding platforms. and thus praise their modded experience over the actual vanilla experience. All i have to say is, If you're gonna put in that effort in making a game better, why don't you put in that effort into making a new game?