I partially agree with you there. We monitor the temperature of every switch at Cisco Catalyst. Simply for the reason that if a fan fails or a neighboring device generates too much heat, we can proactively intervene.
An MT sensor in the rack is a good thing to be able to assess the overall situation, i.e. is the air conditioning running or is the rack getting too hot. We have already tested MT at the rack front and the back, provides good information.
BUT, this information does not help me for a single device or even small racks where the MT would have no connection.
This is such a simple thing, Catalyst can do it and Meraki can't?