The device draws what it draws regardless of class, and forcing anything seems dangerous.
The motivation for 'forcing' is because the vast majority of devices identify by default as class 0 (Mobotix cameras are an exception), which means that the switch has to be prepared to provide 15W at anytime to power it. These devices typically don't draw anywhere near the max, though ever.
Because of this possible demand switches will pre-allocate part of their budget to the device, whether the device needs it or not. In a switch that doesn't have a power budget big enough to provide full power on all ports, this pre-allocation can end up starving later devices that come on line needlessly.
So you might want 'force' a power class of 2 on a device that you know only ever draws 3W. This causes the switch to pre-allocate about half the power it normally would, which is then available to other devices.
There is some risk in doing this, but that's the reason to do it.
In the case of the Razberi switch, this is not necessary as it can provide full AT level power to all ports at the same time. Contrast with the Nuvo switch shown above, it only has 160W for 16 ports, so such a strategy might be helpful if pushing the switch near its limits.