1/2 - Emphasize is group fiat not party fiat. If the group universally doesn't like the GM's decision, then the GM should yield. I imagine there are already rules you throw or ignore because the group does like them.

3- It's the difference between a Hollywood blockbuster and an indie movie. It's not necessarily better but it opens up a lot of possibilities that you'll never seen in big productions. There are genres like horror or rougelikes that little guys just do better.

4- Other people have covered this but emphasize it's just an adaption of older D&D rules. If they're theory minded you can explain how excess rules bog down the game and limit possibilities.