Why do some think the need to own a gun is higher now than in the past? Why do some think that the need to own a gun to protect yourself is increasing? I could see an argument being made that the danger posed by the Republicans in government is greater now compared to before, and the danger posed by the police is greater now compared to before, but I don't think this is the sort of argument that some intend to make. Moreover, violent crime rates have been dropping in the nation and around the world for the last few decades due to the prior banning of leaded gasoline, and so if gun owners are going to make the argument that you're likely to be attacked by criminals today, then you're simply wrong.
In some ways, the second amendment is a historical aberration which doesn't fit perfectly with modern times. I am unsure how the founders would react on this issue today (not that their opinion is all that important), but for my bit of historical speculation, which has only little bearing on proper modern jurisprudence, is that the founders would demand the following line: The police must obey the same rules for weapons as everyone else, and everyone else must be afforded the same opportunity to earn the same licensing and approval to carry and use weapons in the same situations as the police. The founders just fought the War Of Independence to get rid of the police, and above all else, they wouldn't want the police to come back. (By "police", I mean "police" with special powers of carrying and using weapons, and special powers relating to detention, arrest, search, and seizure. Everyone should have the same weapons rights, and the only kind of arrest should be a citizen's arrest or an arrest by warrant.)