I think the service rule should be change so that it's fair for everyone wether your short or tall, there should be a rule that the shuttle can't be raise more than 1.3m form the ground so if your short you can only raise it up to 1.3 and if your tall you can only raise it up to 1.3 as well, so this way there's always a loop or lob when serving and anything over that should be called a fault. at the moment the ruling is waist height but everyone is different height, a lot of pro player espescially the tall player look like there serving flat it's still legal because of there height. please let me know what you think.
The rule is good the way it is. Even when a tall player serves the shuttle still comes from below. I don't think it's a great disadvantage for a small player when it come to serving.