I can't tell you how many people I've played who never realized that the wording on hand limits allowed them to choose to observe the limit or not during their turn. Even seasoned fluxx players have told me they never thought the, "may ignore the hand limit," text would allow them to discard unwanted cards.
Wow, this was food for thought! The applicability of doing Hand Limits during your turn was obvious to me. At Origins I lost my first game in the Zombie Fluxx tournament because of a kid who loved the Play All card. He played it, I trashed it, he did Let's Do That Again, and I was forced to lay down a Goal that let someone else win. A Hand Limit card could have helped me avoid that.
Still, I had to think through what it meant to do it during your turn. I concluded that if you were following the Hand Limit rule, you had to do it all the way - that is you had to discard all the way down to the limit. Just discarding the cards you didn't want to have, then following Play X rule, then discarding "the rest" needed to match the Hand Limit, feels like cheating - you wouldn't be following the Limit, you'd just be discarding.
So I was glad that when I did a search on 'Fluxx "Hand Limit" may', I found this video of Andy explaining this very scenario: http://www.youtube.com/watch?v=SuGynyj6D-c . In it he discards all the way down to 2, rather than discarding only the unwanted Goal.
Thanks for mentioning this! Bryan