No, it isn't always the case. Some casinos have very complicated registration processes. Some casinos, for example, require a KYC procedure immediately upon registration, while others do not even require an email confirmation.
Oh! I have just understood what is meant as easy and hard registration process. I remembered when I registered at bet365 many years ago, I was to provide kyc and I provided it, all did not take more than 10 to 15 minutes, I have not seen kyc as stressful but that is true that a gambling site that requires only email is easy for registration than the ones that will demand for kyc, some people might even have difficulty while providing the site their kyc, some will even be rejected or addictional kyc might be demanded for.
10 to 15 minutes is super fast for a KYC approval because usually KYCs are approved for days or longer than that because they carefully check the details if it was really from that person uploading it and not just by a random ID's that they get or bought online. Speed of KYC approval is not enough for the gamblers to sign up but there is another thing that they are worrying of. That is their privacy being shared to the casino.
Aside from the email being needed to sign up, there are now newer casinos that uses the web 3 technology where you can sign up instantly and start playing by just connecting your crypto wallet. It's a cool feature.
I have seen recently introduced casino here using web 3.0 services, which is actually helpful for those gamblers who just want to connect their webwallet like metamask in order to play. I believe, in the near future, this will be the new trend to these crypto gambling casinos. Gamblers can directly connect with their online wallet.
On the note about the important features, the leading aspects in the poll are customer service and responsiveness to complaints, which, I can very well agree. If the casino is treating their players at their best, they will always be one message away if the player encounters any issues with his game. And they will try to resolve it promptly. So even if we say, their withdrawal fees are a lot higher than other casinos but they have good service, I would go for them because I have the peace of mind as a player.