I have to disagree with you here. You shouldn't need to buy a separate addon pack, maintained by another developer. It should be in core. Extra plugins are just extra bloat. The advantage Oxygen holds over other builders such as elementor is leaner, cleaner, faster code. Adding addons is simply detrimental to that. They've clearly been heading that way anyways, such as the new woocommerce mini-cart element.
Implementing them in core also allow better implementations. I don't think any third party dev can do it better than the builder devs themselves.
Also have to disagree that the price of Oxygen would be higher. Builders are always striving to improve without raising costs. Elementor can get away with it since they have over 5 million installs, and they have a captive user base. Oxygen is niche enough that they still haven't reached critical mass, so raising prices would be foolish. And even if they did, Oxygen is a buy once lifetime license that can be used on unlimited sites unlike Elementor's yearly plans. Plus, this site is nulling Oxygen, so the price doesn't even matter.
> plus the maintenance of all these would cost extra effort for the devs, which would result in even slower development of the acutally important aspects of the builder
This is going to happen regardless. It already is developed at a glacial pace, extra features don't really have any impact on that. The reason the development is so slow as far as I understand it is that the Oxygen dev team is incredibly small, just 2 people.
Each to their own, but you're probably missing the mark that Oxygen is made for coders to ease their life, rather than drag and drop non-coders.
"I don't think any third party dev can do it better than the builder devs themselves."
Why? There's no reason to put them on a pedestal over other 3rd-party devs. 3rd-party devs can focus on making their sh** awesome. Here's a perfect example: Music production. Wether you choose Ableton, Logic, Cubase, FL Studio, or whichever other software, the 3rd-party plugins you have for a certain thing to achieve, blow the sh** out of the built-in instruments and effects. And the DAW developers know that don't strive to try to be amazing at everything. They provide an amazing core/platform, and the 3rd-party devs provide hella amazing additional plugins that do other sorts of things in a very polished way. Does Ableton have a built-in reverb effect? Ofc. Does it work well? Sure it does. But when you install Wallhalla Room, it's a gamechanger reverb effect. All because that company is focused on making reverb the best it can be, and nothing else. Should Microsoft Windows provide something more powerful than Paint pre-installed? Something like Adobe Photoshop level graphic manipulation software, just because some of the users will need it? Do you see the issue here? Just because you need that, I and someone else doesn't... And we don't want it pre-installed because someone else will need it. The platforms should stay as clean of any optional stuff as possible. And apart from the basic elements - those that everyone needs and uses, nothing else should be pre-included.
"Extra plugins are just extra bloat."
Extra elements are not extra bloat?

Extra built-in bloat you can't even choose to not have...
One big plugin with built-in bloat is worse than 5 well coded smaller plugins. It's not the number of plugins that slows down a website, but the quality of them. You can have 5 plugins and a slow website, and you can have 18 plugins and a fast website - depending on the quality of the plugins running.
Learn to code! It's where it all starts...Or just get a different tool that supports your vision of fiddling around.