the amount of pictures on your phone absolutely should not matter. They can certainly code around that. Why should my device be crippled if it's full? I bought a 16g phone and should be able to use 16g without performance issues.
If I bought a 64g phone and had a full 16g occupied, should that impact the performance? If the internal hardware is the same except for storage, it shouldn't matter one way or the other.
iOS needs free space to handle system and app caches. These caches will increase or decrease in size, depending on usage. EVERY OS will slow down if you insist on running the device at or near its storage capacity. No amount of coding or wishful thinking or ranting or polling about criminal activity will change that.