There are valid reasons as to why Rockstar should and shouldn't actively balance items in GTA Online.
Game balance is often a delicate matter that is bound to throw people into a frenzy whenever it's brought up. However, seeing as though GTA Online is an online multiplayer game, it does make sense to compare it to its contemporaries in this regard. Most online games do buff and nerf items to change up the metagame, but GTA Online, interestingly, does neither.
GTA Online's laissez-faire approach is appreciated by some players, but there is still a discussion to be had about whether Rockstar should or shouldn't actively balance items in GTA Online. Some game companies do a terrible job at balancing their game, but others do a superb job (although fans will still complain no matter what), so it's also important to see why Rockstar doesn't actively attempt to.
Should Rockstar actively balance items in GTA Online?
One of the most important reasons for actively balancing items within a metagame is to change things up. A stagnant metagame gets boring over time, and that's not even mentioning how some items are left in the dust for years at a time. However, just as there are valid reasons for Rockstar to actively balance their game, there are also good reasons as to why they don't do it.
Some reasons why Rockstar should actively balance the game
Changes to the game don't have to be extreme. For example, Rockstar wouldn't have to remove the Oppressor Mk II's ability to shoot missiles; that would be a terrible approach to balancing. Instead, it could be something minor, like changing the price of old vehicles, such as the Rocket Voltic. Discounts from time to time help, but they're not a permanent fix to an otherwise overpriced piece of junk.
Alternatively, Rockstar could seek to change minor aspects of certain vehicles. For instance, the Chernobog is far too vulnerable for its supposed niche. Just giving it extra armor against explosives could help it get used more. Of course, buffs don't have to apply solely for vehicles.
Something like SMGs could use any kind of buff to have a larger role in the game. Likewise, obsolete weapons that aren't unlocked at the start (hence the early-level vs higher-level argument doesn't apply) could use a little flavor to not be a meme. Anything in the game could get buffed, ranging from businesses to Shark Cards, as there is a lot of material to write about on that front.
As far as nerfs go, some elements of GTA Online are overcentralizing. In the case of the hated Oppressor Mk II, it simply does too much. Outstanding mobility, great weaponry, and it has the ability to fly. A minor nerf to one of its frustrating aspects would greatly appease GTA Online's playerbase.
Should Rockstar actively balance items in GTA Online?
As it stands right now, there's no need for Rockstar to actively balance items in GTA Online. It would've been great if they did it over seven years ago. Sure, the phrase "better late than never" could apply here, but balancing a game is not so black and white.
Rockstar likely did the numbers and found it to not be a profitable venture. While it would be nice to entertain the fans, at the end of the day, it's still a business. Businesses need to make money, and if actively balancing items in GTA Online doesn't do that, then there's no need to do it.
Some reasons why Rockstar shouldn't actively balance the game
If it ain't broke, don't fix it. That's an old motto, and some fans could argue that it applies to Rockstar's current approach to balance. As it stands right now, GTA Online is a highly successful game, so it's not in need of being changed. If change is handled poorly, then that would hurt the overall reputation of the game.
The above points are relevant since GTA Online's current success means that active balancing attempts aren't warranted. There is no immediate need for Rockstar to waste money on pushing out balance patches, if they're already raking in a huge profit with their current model.
Plus, some changes would anger parts of the fanbase. Sure, some players would love to see the Oppressor Mk II nerfed to the ground. However, that would only anger those who bought the bike at full price and genuinely enjoy doing the things they do with it. Balance is a delicate matter, even in a game like GTA Online, so it's not as easy as simply saying "Done."
Rockstar's current approach
Currently, Rockstar likes to do bonus money and RP events for various activities. It's not a permanent buff to some of these activities' viability, but it certainly helps diversify normal gameplay. As far as nerfs go, the only "nerfs" are bug fixes or introducing new, better content.