I agreee with this, though these are not all such kind of the minis that should have such restriction...
-Morannon Orcs (since there were few of them) should be played as powlers... [ I like them and play with them a lot but aprat of that they should be no such a domianting orc race on table...] or how about 33% of the army? (herose not included)
-Iron Guards???
-Besrerkers...???
-and all kinds of elites...
I´m not so sure about this but maybe some herose too? like I doubt that Elendil would go out with a scout party... maybe something like this He may be icluded only if there are Numernoreans for 100p on table??? a captain would be suitable for such a job...
Same for Dark Lord...no really I doumpt that he would venture alone with out his hord army...
and lot´ś othere herose
this would keep the players for fielding umber herose and a few troops what makes the game really boring...
well there are some exeptions like Aragotn the Strider, Twins and Gandalf... and ofcourse othere wanderes
Another example would be...how likely (In LOTR ofcourse) would rangers of gondor meet a single Mordor Troll Chieftain wandering alone in Ithiline... More likely an Orc Cap. and some Orc scumm but not such a creature...