When Dark Souls came out, very few games were anywhere close to its level of difficulty, world design and mystique. The interconnected level design, as well as memorable areas and bosses made it very easy to make a mental map of the world and to traverse the landscapes. Also, the difficulty curve of the game just sort of sings to certain people, and again at the time of its release many other games were going the exact opposite direction for difficulty and hand holding. Context is everything, and those who fell in love with the Souls series because of DS1 can't simply be scoffed at and told "it's bad" almost 6 years later.
- Need to be human to summon, but lose your humanity along with your souls
Yes. This was a fundamental mechanic for humanity, and was an interesting gameplay twist that opened you up to envasions, but gave you the opportunity to summon. Also, if you're referring to losing your humanity along with your souls when you die, that's also a compelling mechanic that added to the sense of doom and depression that the title was trying to convey. It instilled a fear of the hostile environments and enemies and encouraged that you take you time to review your surroundings before pressing on. It's great.
- Can't fast travel between bonfires (at least until way late in the game?)
Again this is a key factor that made the interconnected world so amazing. You didn't NEED to fast travel, since everything was connected and was never more than a few minutes of walking away. But you
had to walk there, which meant you had to go through the enemies again. Do you see the gameplay loop? Treacherous environments with tough enemies that you had to fight or avoid, but if you failed you had to go back and try and recover your souls. It's dangerous out there, so be careful and learn to fight/run better. It's overdone and people think others are serious, but that's where the whole "git gud" joke came from.
- Can't light bonfires when a summon is around.
Ok, and? You've turned on easy mode with a summon, so there's a penalty. Other games have restrictions like this on lower difficulties, and Dark Souls is by no mean willing to hold your hand. You wanted an easier time? Guess your checkpoints don't matter then. Brutal and succinct, and I love it.
- Garbage Estus flask implementation
"That's just like... your opinion, man...". And it's a wrong opinion if you ask me. Best estus system in the series, bar none. You want more healing? Gotta save up that delicious humanity. But what if I want to Co-Op? Well, better have more than 1 humanity. But what if I don't? You can try farming for some... or you could do some tasty invasions to take it from others! It's an intriguing system of counter balance that you don't get in the other games. But hey, once you kindle the bonfire once, it stays like that through the rest of the game and even into NG+, so that's nice. Just make sure you can get back to the bonfire (do you get it now? the gameplay loops! they're looping in on themselves!)
- Molasses movement; super slow sprinting & anything below fast roll is a bad time
Movement is fine, just need to find the armor/weight that works best for you. As for fast rolls, Giant Dad would like to have a word with you in his office.
- Dope PC port that requires several mods and tweaks to run decently
Sure, you're not wrong there. But you have to look at the context of the game's release. FROM had never made a PC game before, and it was a console exclusive until there was a large enough outcry from the community for the PC port. It was rushed and poorly optimized, but again it was done by people who'd never done anything like that before. Also, if you're really going to complain about the super simple DSfix... I mean... really? Durante did an amazing job with it back in the day. But I digress.
All in all, I believe that your opinion is bad and you should feel bad, but it's whatever. Play what you like. For me, Dark Souls 1 is still the best of the franchise (don't have a PS4 for Bloodborne, but I know it's amazing) simply because of what it did for the industry back in 2011 and how well it's stacked up today. Play it every year and I still love it.