A dimmer that reduces voltage properly as you'd expect, is called a variac. It is about an 8" cube (0.2 m) and weighs 50 pounds (23,000 g), and probably costs $300.
The second most obvious option, a resistive dimmer, is called a rheostat. It is cheap enough, but it makes an insane amount of heat, so the provisions for heat removal will be quite expensive.
As it happens, the semiconductor revolution has given us a rather cheap device called a thyristor or triac. It insulates (blocks current) - until you send a "gate" signal to turn it on. Then it conducts, forever. This device is pretty useless, since it cannot be turned off. Ever. However, if current stops flowing, it turns off by itself, and then awaits another gate signal. The triac has very close to zero voltage drop across it, which means it runs cool, which means it can switch a LOT of current at a cheap price.
Now, electric power is AC. (see where this is going? I bet you do.) AC reverses itself 100-120 times a second - voltage crosses zero, and with a resistive load (incandescent light), current goes to zero at the same time. This "dimmer" practically builds itself, AC's zero crossing turns it off, you just need to know when to turn on, and that's a simple timer circuit.
That is the leading edge dimmer you are complaining about, and it's cheapie cheapie cheep cheep.
OK, you want a different kind of dimmer? Now you need power electronics able to forcibly interrupt AC power under load, when that load could be enormous, and potentially inductive. Which is really hard to interrupt. And it needs to fail non-deadly or UL won't approve it. We're no longer in the realm of the 3-cent triac. And the triac has set the customer expectation for cost and heat dissipation.