Showing masturbation is fine as its a normal activity but portraying it as scandalizing is where it goes wrong. Reading the comments here it seems the director wanted to scandalize it and made it an issue, that makes it cheap.
Next showing a daughter imagining her father having sex? is that normal? I disagree. Its not about culture but about values and principles. Had it been accidental entry into the house and she happens to see that could have been better. May be the director faltered here. If there are people who are taking it as actually happening and some as imagination of the incident in the movie, that itself shows the incompetency of the director in handling such a scene. What was the necessity to show it when he was not clear? They could have implied it if the intention was truly well meaning.
And NO sensationalizing sexual needs and desires is NOT modern but pervert and disgusting. Besides Modern does not mean free and open sex.