I'll answer several of your questions/points as best I can:
When to sub:
I'm not talking about situational subbing, rather when to take out tiring players.
At some point in any game, a player's effectiveness declines based on stamina--or else what is the purpose of stamina? What I'd like to see is the ability to rotate in players so no one's on-court ability drops too much before they take a rest. This does NOT mean the BB's should reveal the tiring algorithm, simply that we managers can allow for it and plan for it. Check out Draft Day Sports-Pro Basketball for a solid way of implementing this. There is a free demo. Situational subbing is somewhat accounted for in this PC game, but not really. You're right, it is too tough to implement--but IMO, not needed.
As to the suggestion forum, I have already proposed stamina changes like this several times, as always to no avail.
I will suggest that having all of your players with STRONG stamina is not a very good managerial move.
Perhaps in BB it is not, but it SHOULD be. Why should having supremely fit players be a liability? That is extremely unrealistic.
I didn't mean FCP or 1-3-1 are gimmick defenses. The new box and ones are gimmick defenses. See any discussion of these defenses on coaching websites.