This one is actually pretty straightforward for me. Sure, I will use it occasionally if I have the incentive. However, I don't think everyone would agree that LN is really necessary for casinos to become more user friendly. Some gamblers invest a substantial amount of money for their "entertainment", so the transaction costs of the Bitcoin network are not a huge concern under the current circumstances.

Depending on the situation, I can see potential for Lightning being used for a lot more than gambling, and will likely see it implemented in many applications in the future. But for now, using the mainnet is still more convenient for the end user.

I agree with this I am sure users wasn't really that concern about the fee since they have money to sustain their gambling hobby and I think the fee right now is not that expensive and it is not all the time that it is expensive but it is better to have the Lighting Network available if possibile since some users may really don't have budget or limited budget for their gambling and this LN could be really useful.

I wouldn't use the lightning network even if it were available since I have gotten used to using BTC and other popular altcoins and I never faced any major issues with them so far.

Many crypto gambling sites that I gamble in don't charge deposit and withdrawal fees and the TX speeds are pretty fast. I know that the lightning network transactions are faster and cheaper in comparison, but I am not really interested in it.

I think that some casinos that offer provable fair betting can greatly benefit from the Lighting Network. It is basic rule of the business - even if only 10% of the people that uses you site or casino can benefit or wishes to use the LN is a really must have or else the site will be spending money in marketing to that people that eventually do not join or join other sites because they do not feel correctly served.

I think I wouldn’t use lightening network even if they were available because I don't need fund on casino regularly. It’s like, I deposit and play for few weeks, sometime even a month. Also, there are alts through which we can deposit for almost free.

^That's right, LN is not a big deal anymore and I don't think the casino will support this LN because it seems through transaction gambling casinos also have a benefit on it. As we can see gambling operators have their own transaction fee which I think they also earn on it and even though a gambling casino that has a free withdrawal did not even use this LN. Probably because LN transaction is good for bulk transactions only which is not good in many gambling platforms because it has an only individual transactions.

Sure I will and I even invite everyone to use it not just because the transactions are faster and have lower fees but also because using the lightning network helps the bitcoin network as a whole by reducing the number of on-chain transactions which will result on lower fees.
I use nothing but bitcoin so if the network is congested (high fees + slow confirmation) and the casino does not accept zero-confirmation transactions, lightning payments are the best option for me.

Besides, using LN isn't as complicated as it used to be in the past and most reputable wallets support it. So, there is really no reason not to use it.

I'll register to one of them, and try it through simple steps anyone can do using BlueWallet, a mobile app. I hope I win so we can see how withdrawals work. Plus another problem for regular Lightning users is converting their coins offchain to onchain. They need use a service like, https://zigzag.io/#/ which requires the user to pay more fees. I believe those casinos/gambling sites should give a choice for both offchain and onchain withdrawals even if the deposit was offchain.

Unfortunately, not too many gambling sites use LN yet.  This list just reminds me of some kind of experimental testing of LN for the cryptocurrency gambling industry, and not regular use as it happens for other cryptocurrencies.  It is possible that there are not too many users yet due to additional manipulations with the wallet and some complication.  Perhaps most players are just too lazy to understand LN? 
And this is disappointing because you can play with LN with a very small amount of Satoshi.  And this is important for countries where the level of income of the population and the general standard of living are low compared to European countries.

The people who don't know about Lightning Network.For them
"The Lightning Network is a "layer 2" payment protocol layered on top of a blockchain-based cryptocurrency such as bitcoin or litecoin. It is intended to enable fast transactions among participating nodes and has been proposed as a solution to the bitcoin scalability problem. Source:Wikipedia"
If there is no option without Lighting Network then I will use them . Otherwise there are more option I mean there is lot of alternative coin who give low transaction fees.