Dry food is absolutely horrible for cats. Cats get most of their moisture requirements from their food - they don't have as strong of an "instinct" to drink water. So if they are on dry food, they are on the path to potential health problems including kidney issues, urinary tract issues, and dental issues. I believe there's a sticky here in the forum that goes into more detail about why a cat should be fed "wet"/canned food, grain-free, with a protein (meat) as the first ingredient. (i.e., the canned Science Diet/Hills foods are just as bad, as they are full of grains and flours that cats simply cannot digest.)
Your vet, in all honesty, probably gets a commission from selling Science Diet and Hills foods. They essentially profit from pushing it onto every single client. Or, it's also possible that they simply do not understand feline nutritional needs (I don't believe vet training includes nutritional schooling), so they think that a dry, grain-based kibble is perfectly acceptable.
There is absolutely no medical reason that I can see that a 6-month-old kitten should be on some kind of prescription diet. Unless he is already suffering from an illness or condition, get him off that food ASAP.
I'm an advocate for raw diets, personally - when I switched my cat, who is now 17 years old, to a fully raw diet 3 years ago, her poop literally does not smell. At all. I can stick my face an inch away from the litterbox and I smell nothing. Her poops are small, dry, and powdery-white, indicating that she is digesting and absorbing nearly all the nutrients from her food. That is why a kitty on kibble/grain-filled canned food lays huge, loose, wet stinkbombs in the litter box - they're passing all the crap they cannot digest, like grains, by-products, and basically anything plant-based. A cat on a raw diet, or at least a high-quality meat-based canned diet, will have FAR less stinky poops.
There are a lot of commercially-available raw foods out there - some are frozen, some are freeze-dried. But I know the raw life isn't easy, and it's not for everyone!
However, I would absolutely switch your little guy to a high-quality, grain-free, real meat CANNED food brand. Innova is good, as are Wellness and Evo. Ziwipeak, Dave's Pet Food, Natural Balance, Blue Buffalo, and my cat's personal favorite Weruva are all also excellent grain-free brands. Honestly, even Fancy Feast Classics (which are actually grain-free!) are better than even the "highest quality" fancy kibble.
Sorry to go on such a soapbox ;} I feel very strongly about my kibble-hate and I believe a lifetime of kibble (before I learned better) contributed heavily to my cat's kidney failure (CRF/CKD). It's much better to switch a kitty over to canned before they become hopeless "kibble addicts".
TL;DR, I see no reason why your kitty has to be on Science Diet/Hills; you absolutely should switch to canned Evo or whatever brand you want to try :}