It will always be a good thing if you are going to give some tip to a person that gave you a good service.
Treat it like a gift to him.
You are right it is not that bad to give a tip as a gift for those people who are giving good service to us. And for sure they are going to appreciate any amount and that's how tipping works. It's not all about the payment that we need to give to them but it's just a simple token of appreciation that we are loving what they did to us.
You are right about tipping is for the token of appreciation. But sometimes, tipping is also for giving other people who are badly in need. I'm speaking on gambling tipping. Because i think you are pertaining on tipping for the great service just for free. I always tipped other user everytime i won huge btc with no string attachment.
It also depends on the site you are on. Some sites even if you think you are tipping the dealer or the person working behind the counter that you are interacting with, the money goes straight to the site and not the dealer. Whenever you feel like tipping, please ask the dealer if they get to keep the tip or is it going to the site. I have come across a couple of sites where I tipped thinking it would go to the dealer but they denied when asked about it. May be the casino owner then splits the tip money later or may be he just keeps it for himself. I do not know about that.