Cheaper, brighter, easier, faster, even more customizable. Better than minis on all counts.
They have their own problems. IDing the token can be solved by someone doing some decent token design.
All counts?
There are several problems with tokens, not just the main ID one (which is the one that bugs me the most).
They are hard to see at an angle. They sometimes have a glare off of lights from some angles. They can more easily slide under a map edge. To see this "decent token design" that you are discussing sometimes requires that players lean further over the map.
Being two dimensional, they also have less visual surface area than a miniature. Miniatures can more easily be visually differentiated via not just multiple colors, but height, width, accessories like weapons or wings or shields.
Tokens are just plain too small to be visually appealing.
Miniatures can also represent prone easier (whereas tokens represent bloodied easier). And there is the ID issue of many tokens (at least the WotC ones) looking pretty similar at any distance over a few feet for us older people with eyesight that is getting worse over the years.
As for numbering, we used to place numbers on all of our miniatures. We haven't done that for some time, but there are tiny colored stickers that can be placed on the bases and a DM could easily have the non-unique monsters (such as a group of undead) numbered for each one. Unique monsters don't really need that.
Tokens make good minions and are slightly easier to place conditions on. Beyond that, miniatures are vastly superior visually and give a better sense of the effect of the game. Just like quasi-realistic looking maps with grids on them are vastly superior visually to the "rough drawings on a surface" that we used for decades.
Visually, playing with tokens is like playing with chess or checker pieces or coins. It's going backwards in time. Using them is like going back to the days when people rolled a D6 and a D10 to represent a D20 because most D20s were the "soap dice". I don't want to go back to those days either.
There is definitely a market for tokens because they are cheaper and more portable, but you get what you pay for.