If you're flying 101, then you know you don't need "clearance." If you're flying 107, then isn't the procedure to notify online?
Consider that five other aircraft, all manned, might be requesting clearance at that moment, while you, who doesn't require clearance, is asking for clearance, and you're using the radio to do it.
But you're right - if the tower doesn't mind, then there would be no reason not to use the radio.
I just checked.....Your correct, under 101 all you have to do is give "prior notice".... it says nothing about how prior of if the tower can deny permission.....
1. Model aircraft that are operated in accordance with Part 101 Subpart E, Model Aircraft), which applies to model aircraft meeting all of the following criteria:
• The aircraft is flown strictly for hobby or recreational use;
• The aircraft is operated in accordance with a community-based set of safety guidelines and within the programming of a nationwide community-based organization;
• The aircraft is limited to not more than 55 pounds unless otherwise certified through a design, construction, inspection, flight test, and operational safety program administered by a community-based organization;
• The aircraft is operated in a manner that does not interfere with and gives way to any manned aircraft;
• When flown within 5 miles of an airport, the operator of the aircraft provides the airport operator and the airport air traffic control (ATC) tower (when an air traffic facility is located at the airport) with prior notice of the operation;
• The aircraft is capable of sustained flight in the atmosphere; and
• The aircraft is flown within Visual Line of Sight (VLOS) of the person operating the aircraft.