It would be very good to earn more RPs and satoshis at Wheel instead of lottery tickets, but I think it's part of their balance strategy to not give too much money away to users, what could compromise the platform's sustainability. They have to pay every single satoshi to users, while RPs I doubt it's everyone who swaps it, because it's needed to accumulate 100,000 RPs first, so it's likely not every RP paid is going to be converted to real money, but lottery tickets they can give million without necessarily having to pay anything to users, as only few people win the final prize.

I believe lottery tickets are just a consolation prize to not let the person go away without receiving nothing from his roll/claim.