I like creating my PHP functions using key=>value pairs (arrays) as arguments instead of individual parameters.
For example, I prefer:
function useless_
This borders on Cargo Cult programming. You say this is more readable and self-documenting. I would ask how? To know how to use your function/method I have to read into the code itself. There's no way I can know how to use it from the signature itself. If you use any half-decent IDE or editor that supports method signature hinting this will be a real PITA. Plus you won't be able to use PHP's type-hinting syntax.
If you find you are coding a load of parameters, especially optional parameters then it suggests there might be something wrong with your design. Consider how else you might go about it. If some or all of the parameters are related then maybe they belong to their own class.