I waited for this period in order to understand if my idea is just the product of a stale conviction left to rot for months or something that has to do with the realm of reality.
While not armed with a screenshot from a dev saying 'I flippin hate the first Dark Souls (from here DkS), I have reason to believe, reinforced by some suspicious actions against the main game, that FromSoftware is actively sabotaging Dark Souls: Remastered PC in order to prevent people from acknowledging how more solid and enjoyable title it is compared to its sequels.
Let me list my arguments before you see me as an internet madman with a tinfoil hat and anti aliens bat.
It came out in a period where a lot of other games got their remastered either for free, or with the new version 'absorbing' the old one (like the devs of Red Faction Guerrilla did) but for some reasons, the one got by Dark Souls 1 was the only, or among the very few ones, to have a price tag even for who owned the previous version. 20€ for a game you already own isn't a real deal if you ask me.
DkS 2 got as well a remastered back in its days, but the previous wasn't removed from the shop. While it is true that Sin of the First Scholar is more like a light remake than a remastered, so if someone prefers an easier version can play the original one, but still I cannot see any real reason to remove the Prepare to Die Edition especially when, because of the lack of anti-cheat, it is the preferred version of modders and people who like to challenge themselves with custom playthroughs.
But with the next point we'll see effectively, maybe, why this happened.The game almost never goes on sales on Steam. With the Christmas sales going on, you can see by yourself everything has a nice -X% over its name, but DkS: Remastered and a price tag of 40 bucks for an old title doesn't scream 'buy me'.
So, here what I think it happened. They didn't want the original to sell more than their next titles so they used the Remastered as an excuse, to remove the old one and disrupt the community, now divided into two different games that cannot connect to each other with the new players maybe preferring the latest title because of the way more active community and the 'veterans' appearing like grumpy old virtual users who cannot like new things.
me illustrating my indisputable reasoning
Reality? Overthinking? Too much expired estus? I don't really know. Maybe it was just a very bad marketing decision and they really thought it could've worked and I just need to pour other more hours on DkS 1.
I just wanted to give a solid appearance to my thoughts, and here we are!