Would like to suggest to simply leave the replay launcher button on the patcher always available, regardless if the server is undergoing maintenance or not.
How about instead of having the "Play Classic" button always available, just make/place the replay button there for scenarios when the server is down, crashed or undergoing maintenance.
At least then one could watch their replays anytime, offline or not. Or even share them with friends and have them able to instantly view them instead of forced to wait for whatever problem or maintenance to be resolved.
Mild frustration with a simple fix.
I am assuming the choice to disable the replay in failed to connect or maintenance scenario is for the rare chance that the client is not up to date and a player tries to watch a replay resulting in errors. But that seems silly as that would be a extremely rare situation.
Most of the motivation to watch a replay comes from downtime or shared interests. Why not make that available for downtime situations like maintenance and server crashes?