Sources should be able to specify the latency they want
Icecast has a lot of options to trade off latency vs smoothness, e.g. pre-burst, and will probably have more in the future.
It is really really annoying to have an interactive live stream, e.g. where people are responding in realtime over IRC or other streams where the pre-burst is adding 5 seconds of delay. And it's a pain to go get access to the icecast server in order to turn off these features, as the server operator may not be easily available.
The stream source knows best if low latency is required. To the extent that the high latency features impact server scaling it may be useful if the server can still limit them, but absent forcing on the server the source should have a way to select.