Why are you speaking about fighting? The rules for UM 100 success and similar apply to maneuvers and even though they could happen during a fight you can hardly say that maneuvers only happen during fights or even that this this is the typical occasion when maneuvers are used.
Well, I referred to fighting because you mentioned minions, but, it is certainly plausible that the maneuver attmpted would be to avoid a fight....often a good idea in RM.
It might be that if your game is limited to low level dungeon crawls the successrate does not matter much, but for those of us that have more high level campaign then what can be done in the setting has a great impact on the play.
Actually, I prefer higher-level games and that is where you find
less chance of any particular action being anywhere around 1% or less, I believe. And I still fail to see how having one 1-in-1000 or so chance of success in 4-6 game session to have a "great impact" on the campaign. Because, if the characters are facing those types of chances each session, then the character turn over much be "great".
My game is not limited to situations when failure has dire consequences. You might be happy with such a limited game, but that ties back into my previous point. That some people want UM 100 short circuiting the statistics is a poor argument for including this as a core rule since there are others who are not fine with this design choice and want this to be an optional rule.
No, not all consequences are dire, but there really do need to be some sort of onsequences to an action (and not ones that would be dealt with easily, like a little lost time) to bother making the player roll for success/failure. The only reason to make players roll for everything is to ensure they fail at something. Because, no matter how good there characters are at what they do, if they are forced to roll several score skill checks per session - be it in combat or otherwise - they are bound to fail several times. And failing things while living the life of an adventurer, means a short career, and very likely a short life. (Which, I admit, would be realistic in a world such as the typical fantasy world. But it would hardly make for a great campaign if the players were forced to make new characters every 3rd session or so.)
Oh, and lest I forget: Every rule is an optional rule.
Umm...you mean to hide the fact that there are a 100 UM rule from the players? Never allow them to look at the tables would allow you hide the rule and its implications but then I must ask what is the point of the rule really?
Funny, but I am sure you know what I mean. The fact is, you don't know the odds of something when you attempt it, you can guess and that can be an educated guess that gets close, but you won't/don't know the exact odds. So, why must the players? (The GM must because he is running the game.) There is mystery, tension, and drama all before you even pick up the dice.
And the point of the UM 100 rule is like many other attributes of most games, a hold over from earlier role-playing ideals where a special roll was treated, well, special. Which is not a bad thing, and it does help to have that special be a little more often than 1-in-1000 (or so), but not be so often as 1-in-10 (or so) which is too much and takes away from the "special" idea. I think that 1-100 is just about the perfect range; you can have a good amount of detail, and not get so bogged down. just a good range, imo.
But, let me try another tack, as to why I think bothering with chances less than 1% is unecessary: Because the 1% chance of success odd comes up so infrequently (or, at least, it should), it is always something special when you succeed against anyway. Saying it was 1-in-1000 instead, doesn't make the joy of success 10x greater, but it does help bog down the game as one tries to determine that level of chance. (Though, I will say, not 10x as much either.) It is all about cost vs. pay-off. Like the fact that we cannot currently make a TTRPG to exactly replicate real-life and all its various attributes, because to do so would make an unplayable game, as it would take 2+ hours to do something in-game which takes 2-seconds in RL. It is about the balance between playability and accuracy, both have to give and take. I think that bothering with worrying about percentages less than 1% (not that they won't be there from time-to-time, just don't go out of your way to ensure they are there) is too much, and takes away from the playability/fun of the RP-ing session.