It's difficult for an online casino to offer more than this to its customers. And about small rollers, I agree that they should also get at least a little bit of compensation for their time and consistency towards the casino. If an online casino starts to offer something like that to its regular small rollers, it will probably get more traffic, as we all know that there are more small rollers out there than high rollers. So retention of small rollers should be a part of their marketing strategies.
for small rollers, online casinos can offer contest like what i've seen in betfury, the $150 free-to-play funfury battle. you can get certain amount of funfury token and use it to bet, and you don't need to spend real money to join. you can test how good you are in betting to get high profits also. so casinos can think of similar concept to small rollers just to engage them in being active on the site. this idea is not hard to implement, if they have dedicated individuals to take care of this feature. they don't need high amount to launch. and look at how many players will join the event.