Obviously, dust settles on flat horizontal surfaces, so having an air intake at the very bottom isn't optimal there. And yes, if the Mac stands in an office with daily cleaning, there might not be much dust, but still, if you run it for 5+ years, it will suck in a lot. If it is in a corner of a small desk with lots of other stuff and not daily cleaning - e.g. at home, there can be considerably more dust.
My MB Pro started failing for thermal reasons after 5 years, fortunately, the local service partner could clean it for a tip. After that, the thermals of the machine were distinctively improved.
Dust in the ventilation is just a matter of time, a machine should not fail because the user can't clean that dust.
I live in a fairly dusty environment that also gets quite hot in the summers. I have to clean my i9 16” MacBook Pro’s cpu fan and heatsink every 3-4 months or else the CPU starts throttling. The MacBook Pro is relatively easy to clean. You just need to know how to remove the bottom cover and the fan plus heating assembly is east to access. But it used to be much easier with the older models. This Mac studio’s design makes it very difficult to clean the heatsink and fan blades. Also the heatsink looks like it has lots of thin narrowly spaced fins, something that will get clogged up really fast in a moderately dusty environment.
I hate to break it to you, but there's not a PC / laptop on this planet that will not fill up with dust and eventually clog and die. You gotta keep your stuff clean. Blow it out with some compressed air cans every 6 months. It's not really that big of a deal. I've cleaned literally thousands of computers in my lifetime, they all get dirty, and if you don't clean them, they will all fail.
Also, I think you are way overstating how dusty this will get. It's not going to be any worse than anything else built in the last 20 years.
Dust doesn't crawl on to a desk from the floor; it settles in from the air. If you're placing a new computer on to a previously dusty surface then, yes, you might see an initial spike in dust coming in. After that, I'd bet that the dominate source of dust is air.
I think the difference there is that the Mac Studio will spend a lot of time with the fans at very low speed, and any dust that settles near the intake during that time will get sucked up later when the fans ramp up. If the intake were higher up the recently settled dust would stay on the desk and you'd only pull in airborne dust.
The front fan grille on my midi tower (Fractal Meshify) collects a lot of dust in its intake, I presume it is because any dust which would have fallen onto the desk in front of the computer instead gets pulled into it by the fans. From my point of view having the intake lower as the Mac Studio would not noticeable increase the dustiness.
Once dust is on a surface will tend to cling to that surface unless it is wiped off or blown off by a significant airflow. A low speed airflow like a fan intake will probably not pickup much of that dust. Most of the dust will come in from the air in the room.
Also, desks and surfaces are usually cleaned.