When you execute "set temp and wait" (109/190/191), during heat up smoothie reports temperature only for selected tool.
If following startup gcode is executed:
(I have really fast bed heater, this code cuts time needed for heat up in half)
State of bed heater won't be known to monitoring software until hotend is ready. And it would be really nice to know all the time what is going on with them. Reporting temperatures for all tools/bed/chamber in case of heat&wait commands seems more sensible to me.
Additionally M105 is processed in-order with movements, so if there is really long/slow movement - monitoring software won't have have state of the heaters neither.