It seems so. There haven't been any new releases for a while, suggesting that they've been discontinued. Maybe it was due to various reasons like low sales or changes in the publisher's strategy.
No, they are not. Intensely erotic stories are not suitable for all audiences. There are different levels of tolerance and acceptance when it comes to sexual content in stories. Some people may be offended by it, some may be influenced in an improper way, especially those who are not mature enough in terms of understanding sexual matters. In a public or general reading context, these stories should be carefully selected and restricted to appropriate audiences.
It's hard to say for sure. Sometimes, factors like low popularity, changing market trends, or issues with the publishing contract could lead to a manga's discontinuation. For Slam Dunk, it might have been a combination of these.