When you end up with a part that needs a lot of steps and removes a lot of material you need a machine that is more complicated, more expensive and with a lower throughput than a machine that simply stamps parts out of a sheet, or shapes them through a mandrill.
Casting is a whole other deal, you end up with different properties because the way you cast has different requirements than creating the raw stock. If the part or product you want to make can't match with the results of a cast part (more than just surface finish) you simply can't use casting (until some sort or alloy is found that delivers the required properties).
You can obviously use other methods, i.e. metal injection, or sintering, or you could simply make it out of plastic. Or you make multiple simpler parts and interface them together (screws, glue, welds etc). But all of those are fine from the construction perspective, but not fine from the aesthetic perspective, and those are valid requirements as well.
The manufacturing method generally is selected during a 'design for manufacture' phase, and that phase only comes after you have already established some parameters on the look, feel, and other properties of the product.
If you could just make it out of concrete or a single injected piece of plastic and still meet all the requirements, they would probably do just that (as the process is simpler, cheaper, higher volume etc).
Fatigue, and failure modes are unpredictable for a lot of alloys.
Machinability, and masleability is usually going in reverse to strength.
Tempering, and annealing to counter the above add to cycle time, and cost.
Some aluminium alloys cold flow.
Aluminium is generally excellent for corrosion resistance against anything you have in your household, but sometimes it isn't.
You can't weld it.
Few things can stick to it.
It's thermal expansion is much bigger than glass, and steel.
That's why I am very hesitant to use it for mass manufactured goods.
ME misses 1 defect showing few months later, and you get n hundred thousand units recall, or worse, the client asking the money back. For a CM it's a complete devastation.
Machining is also very uneconomical unless you can contract high volume machining specialist, but that's impossible for most <1m runs.
Only the biggest PC makers like Asus, and Acer can afford custom casting, and press forging at economical scales, but even they don't go for aluminium everywhere. ASUS for example went with stamped steel shells for some economy models.