As a Roblox developer, it is currently too hard to ensure that all users that enjoy a game click the thumbs up button after playing it. This means that games are likely to get a lower % of thumbs up compared to if the user was asked to give feedback when they leave the game.
I believe Roblox will be able to combat this with a pop-up Window which opens when a user closes the Roblox Player. This popup could request for the user to leave a thumbs up / thumbs down depending on whether they enjoyed your game or not.
If Roblox is able to address your issue, I believe that games will have a better thumbs up %. This is because when a user dislikes a game, they will ensure they click the thumbs down button. However, when a user enjoys the game there is a chance they won’t click the thumbs up button because they don’t need to leave feedback for their experience.