This is text heavy, so bear with me....
Beginning with Painter 2017 or 2018, Corel introduced particle brushes. I believe firmly, Corel needs to expand on this technology and create new and more predictable brushes based upon it. The have created a real (potential) gem with this technology, however the brushes made with it are still too quirky to be usable as, let´s say, static bristle and it´s variants.
The first and most obvious benefit which comes to mind: This technology offers brushes with a changing bristle pattern in each individual stroke. The potential of it goes way deeper though.
Digital painting tools are usually pixel based. A digital brush has as it´s core a brush tip consisting of a static, pixel-based representation of a traditional brush tip. It´s a digital image of a traditional brush tip, which is then used to create an image. It´s an "image of an image"-effect.
The reason to go this way is obvious: The smallest optical common denominator in traditional media is the smallest brush tip available to you in the respective medium you have selected (water color, oils, acrylics, etc...). Two things are important here and pertain to traditional media only: 1st, the brush tip, small though it may be, can still be seen with the naked eye. 2nd, a traditional medium cannot be translated into another medium. You cannot make water color look like oils, etc.
In digital media, the smallest common denominator is the pixel. However, one pixel is too small to be used as a painting tool. Therefore, you need an array of many pixels to get a usable, working brush tip. The way pixels are arranged together determines if the resulting brush tip resembles oil, water color, etc.
This means, in digital media there´s an additional translation process going on to reach from one pixel to an array of pixels as a brush tip, which is completely missing in traditional media. In the end, it all boils down to pixels, which can be arranged to resemble and simulate traditional media, but ultimately stays a static simulation because the pattern of pixels remains unchanging.
I believe it is this additional process of translating one and the same optical currency, the pixel, into a more or less fitting static resemblance of digital media which can give digital media this "unreal" quality of being an image of an image, the latter made to resemble (but not equal) traditional media.
Digital brushes that are not pixel based but instead particle based could finally, at long last, offer digital painting tools that go beyond being a static simulation of traditional painting tools. A particle simulation can be also translated into pixels, but at it´s core it is not based on a static array of pixels lined up with predetermined distance from each other, but on the simulated dynamic behaviour of virtual entities (hairs of a brush) colliding with another simulated entity (surface). The traces of this collision is then what creates a brush stroke. The brushstroke is the byproduct of a simulated dynamic event.
This might offer a way through which digital painting can come into it´s own and shake off the bytaste of being nothing more than a simulation.
On a side note: For some reason, I feel that digital photography is not so much affected by this "image of an image" effect. I believe, the reason for that is in both cases there´s a technical apparatus between incoming light an the image. The kind of recording of light rays is different, and digital media has it´s own advantages (and drawbacks) in the way it records incoming light through a digital camera compared to film.
Very curious to learn other people´s thoughts on this.
If nothing else, I will definitely agree with you that the current particle brushes are too random.