The level of difficulty someone chooses shouldn't matter to you or anyone else.
Now, I love grinding in games, and I always start off on Normal. I also can get bored of a game if it's too easy the whole way through, like a Kirby game. However, unless it's a game that I REALLY REALLY want to savor (kind of rare), if I die numerous times from the same enemy and I can switch to Easy, I'll do it. If I was having trouble on Normal I'm sure Easy won't be too much of a breeze anyways either.
My life is hectic.
I don't have too much time to play games.
I have a backlog of 9-10 games, and there's around 30-35 games that I want to buy and play. If a game is 20-25 hours long that'll take me like a month or more. Longer than that and we're looking at 2+ months minimum.
So, I don't want to waste time replaying a part over and over and over and over and over and over again.
Unfortunately as much as I fucking love Bloodborne (it would've been my favorite PS4 game, by far), I don't think I'll ever come even close to finishing it because of the difficulty. I've also passed on other games because I'm not very used to/good at the genre and the game is known to be hard and has no difficulty settings. For example, my coordination isn't the best (read: it's terrible) so FPS games are very challenging for me. I've had to skip out on some games that appealed to me because they were known to be difficult.
Seriously though, there isn't a single argument the opposing side could present that would be valid. If it doesn't affect you in any way/doesn't harm anyone else, why does it matter how someone plays their game? I swear it's like a debate on LGBT people, but for a video game related topic. And just like how people are more than their sexuality, games are more than just their difficulty level. I didn't buy Bloodborne for its difficulty. I bought it because of the beautiful visuals, the fast-paced and fun combat filled with depth, the amazing art direction and atmosphere, the great music, and the intriguing story premise. It's a shame that I won't be able to experience more than like 15% of it because I'm just absolutely not down to literally have dozens of hours go down the drain from my deaths (and losing blood echoes).