Just some things out of the top of my head:
(Well, it turned out to be a longish rant.)
First, all of you who ask why WotC didn't start with putting out inexpensive plastic miniatures - plastic figures are cheap
only if you make them in very large quantities.
GW can do that for some of their grunt figures (standard orkz, etc), but as soon as they do any kind of special mini, or part of mini, it is metal!
Why? Well the mould for plastic minis costs perhaps (guesstimating from several years old figures) U$ 10 000.
The mould for pewter/lead/whatever minis costs (I'd have to buy it all from scratch), $30-50.
So, if you're not doing thousends of minis that all are identical, what would you choose? Right.
Back to Chainmail, what was good and what was bad?
The combat system was very close to standard D&D - which was good as many know the sytem, and it was easy to port stats from one game to another.
The bad part is that it was overly complicated, not suited for more than ten or so minis per side.
When I look at a war game, I'm mostly interested in CCC, i.e. Command, Control and Communications*.
Chainmail did very well on those.
The command points and the orders were very good. And the fact that you had limited control over most of your figures was very nice.
It lead to a lot of interesting tactical choices.
The morale rules were sketchy, but there's not much one can do in a skirmish game with so few minis. There's not much fun in making break tests for your warband when a third is down, if all you've got is 5 figures.
The miniatures; some liked them, others did not. Tastes vary. But they were too expensive. Yes, GW can charge as much for a mini, but that's GW, and it's for a leader or hero figure, their basic troops are much cheaper.
And why were they not all the same scale? Most of them were nice 28mms, but the gnolls and the female paladin in the basic box were a lot bigger, 32mm or thereabout! (The gnoll trooper is 40mm.)
So, in the end, what about Chainmail? Was it good? Well, I liked it, despite some minor failings. But was it, really, saleable? Could it sell lots and lots of minis?
No.
What I like in a game, the three C's, tactical intricacies, etc, that Chainmail had, doesn't sell.
If you want to sell miniatures on the scale WotC wants, and GW does, you'll have to make a game, and minis, that'll attract the young teenagers, the 13-14 year olds. It's they who buy lots and lots of minis.
And 13-14 year old kids don't care about tactical intricacies or CCC. They just get frustrated when their figures don't do as they want - a lot of the kids I see playing WHFB/40K think that the morale rules are too much! They just want their cool minis to kill all the other minis. (And there's nothing wrong with that.)
I'll stop ranting now, it's getting too long already
* Communication in pre-modern rules is easy. Some games fail even in that, but not Chainmail.