This has been bothering me for the past year or so. In general we have wargames with set "army lists" where each faction or group has its own list and then we have games that allow you to design your own models from the ground up.
The first option generally offers the most "theme" to an army, and if the designers did their job right you end up with a army with interesting strengths weaknesses and quirks of their own.
The second option tends to be more open to "min maxing" and other abuse, and I think we have all seen the comment that the spirit of the game is to build a interesting force with the rules, rather then the strongest. Leaving it up to each player to decide on their force's strength and weaknesses and how that would express itself in the game statistics.
What I have been musing over is that same control of the second system but applied to the whole army first, with less and less options as you trickle down to individual units. Now this has been done to some extend for sure. Many space ship games have a technology level system that limits your options or makes particular choices cheaper. Heck the older war-hammer space marine codex's allowed you to design your own chapter according to different traits, limiting your options but giving you a bonus in return.
Now I am using spaceships for a reason since I think this sort of system would work best in more abstract scales, I cant see it working great at say skirmish level, where each model SHOULD be a individual designed to fit its miniature and background. However at the smaller size of models, 10mm and the like abstractions start to creep in anyway, with the entire unit having a "fire-power" rating instead of individual gun stats for instance.
No real question, just whining why the thing I want isn't out there.