It's pretty standard QoS measure, network schedulers especially for multiplexed/aggregated networks will have a bias for small packets, you should be able to find performance statistics for various token bucket configurations that will demonstrate that.
Do you have a cite for that? :) I know that CoDel doesn't bias for small packets; it treats all flows equally and tracks traffic on a bytes-transferred (rather than packets-transferred) basis.
It's the de-facto MTU of much of The Internet. Baby Jumbo (MTU >1500 but <9k), Jumbo (MTU ~9k), and Super Jumbo (MTU substantially larger than 9k) frames exist, and are supported by many (but -sadly- not all) Ethernet devices.
Edit:
> Also with how global traffic is managed smaller packets tend to get priority...
Do you have a reliable citation for this? I would expect that core and near-core devices would handle so much traffic, that they all would be using MTUs far higher than 1500 bytes per frame.