There have been a few times where I've gotten 5 red envelopes from the present. I was thinking, since the slime boss is something that only happens every 4 hours, that we could remove the envelopes so we have a slightly better chance at getting things that we cannot get by normal means. I can get well over 5 red envelopes in the 4 hours it takes for the boss to respawn to be honest, so it's almost the same as getting nothing at all. Also, the event is already a random chance thing, why give us something else that is also a random reward generator? Thank you!
You're not intended to get everything you want right away from the event - that's why some prizes have a low chance of being obtained from any given box. If they were to remove red envelopes, they would just give the few % chance to obtain it to another common (and likely less useful) reward. I say keep things how they are - variety is fun, and imo the types of rewards for this event are very well thought out and well balanced.