I find it really annoying that so many people including the OP don't seem to get that the very reason for introducing different races to UO is to have different approaches to the game. If every race were the same then there would be no need for different races in the first place. The same goes for skills and templates - if they all could do the same things then why even have variety to select from? All it comes down to is usually to weigh the advantages over the disadvatanges and see what works best for you. In this case:
Gargoyles get to use 5 slot pets and still move at mounted speed while the pet is deployed. The drawback is that they can't hop on their mountable pets to save them when in a pinch. Another drawback is that it is harder to good gargoyle suits, with some essential artifacts not even available for gargoyles.
Human and elf tamers can't have their 5 slot pets deployed and move at mounted speed unless they use high enough ninjitsu for at least llama form (that's around 80 to cast it somewhat reliably). To move with mounted speed they usually use 5 slot pets that are rideable, so getting anywhere unlike the OP claims does not put humans/elfs at a disadvantage, if anything it puts them at an advantage because they don't have to wait for their pets to navigate around obstacles since they're riding them. Now you could argue that mounted pets are not on par with unmountable pets - I have yet to see one non-rideable pet that will outdo any mountable pet. With the choice of lesser hiryus, cu sidhes, nightmares, firesteeds, unicorns, ki-rins, giant beetles, fire beetles you have some of the most important pets to build the way you want and be among the top damagers every time.
Also humans/elves have it much easier to suit up and can use all of the artifacts in the game.
So please Drakelord, take your whining elsewhere but don't make stupid requests when you clearly haven't put more than a second's thought into it.