
There isn’t any need to close the vast majority of gates that appear in Cyrodiil. You can complete the main quest by only closing three gates: the one outside Kvatch, the one outside Bruma and the Great Gate (also outside Bruma). All of the gates are automatically closed after completion of the main quest.
Love Stones, Hate Gates

However, neglecting to close these gates also means you won’t get their respective Sigil Stones, some of the most valuable items in Oblivion. These stones are used to enchant items, and they tend to have more powerful effects than you’d normally get at an enchanting table.
A maximum of 60 gates open during the main quest, meaning you can only get 60 Sigil Stones without using duplication glitches and various other exploits.
If you want to reap the rewards without doing any of the work, there’s now a mod for you. The popular Master of Oblivion mod (by Troybayliss) from the original release of Oblivion has been ported to Oblivion Remastered by R34LM.
This mod adds a spell to your spell list called, you guessed it, “Master of Oblivion.” If used in the overworld (i.e., not an interior), then you’ll be instantly teleported to one of the non-story Oblivion gate interiors. If used while in one of these gates, the gate will instantly close, placing the Sigil Stone in your inventory without any of the fuss.
This spell does not affect gates that are tied to quests, such as the aforementioned story gates, or the gate outside Cheydinhal, which is tied to the quest, The Wayward Knight.
Some players have described Oblivion gates as the “worst part of the game,” so it’s no surprise that there’s an appetite for a mod like Master of Oblivion. Closing a couple of gates for the story is all well and good, but very few people want to close 58 more throughout the game to get all of the Sigil Stones.