Leather boots to drive a motorcycle?

In the Philippines, you have to have a pair of leather boots before you can drive a motorcycle.
This is the implication of a new administrative regulation issued by the Land Transportation Office AHS-2008-015.
This LTO administrative issuance is titled RULES AND REGULATIONS FOR THE USE AND OPERATION OF MOTORCYCLES ON HIGHWAYS.
Under this regulation, drivers will be punished with fine "For wearing of flip flops, sandals or slippers or being bare footed while operating motorcycle or scooter on a road or highway"
The regulation does not, however, give any relevant explanation as to why flip-flops, sandals, or slippers or being barefooted is prohibited.
Neither does the regulation explain how wearing flip-flops, sandals, slippers or being bear footed would have any effect on safety on the road.
Meanwhile, the LTO regulation specifically lists down the outfit that are described as "protectived devices" to be worn by motorcycle drivers.
Section I No. 7 states: “Protective devices” shall include helmet, goggles, leather boots and protective clothing such as heavy pants, heavy jackets, leather gloves and rain suit.
There is a principle that what is not prohibited, is allowed.
So, if only flip-flops, slippers, sandals, or being barefooted are prohibited, are rubber shoes allowed?
What about leather shoes? what about step-ins, bakya, high-heels, crocs (to be a little fashionable)? Aren’t these more dangerous when worn driving a motorcycle?
Where is the rational distinction and valid classification?
Honestly, I find this LTO regulation vague.
Its not clear to me. Its clear as mud.
Any law--much less any regulation--that is vague is void (void-for-vagueness principle).
This is because it drives the people groping in the dark and confused as to how to comply with a law or regulation.