World of Warcraft Classic is aware of the bugs that players had reported during the game's demo - the development team just isn't going to fix some of them. According to Blizzard, some of the bugs that players encountered and subsequently noted during World of Warcraft Classic's demo are actually intended to be there, as they were also present in the Patch 1.12 version of the original game that Classic is based off of.
World of Warcraft Classic is Blizzard's response to years of fan demand for a return to the very beginning of what made the game so great. Originally, fan-hosted "vanilla" servers met the needs of thousands of players, but Blizzard eventually shut them down. The communities had grown so large at that point that they rallied behind the fallen servers to create a movement big enough - including a petition with over 280,000 signatures - that Blizzard finally paid attention, and the company announced World of Warcraft Classic a few months later.
World of Warcraft Classic hosted a demo in late 2018 to give fans a taste of what the company is creating ahead of the game's 2019 release date. According to a community manager named Kaivax from the game's official forums, the development team got "so much" feedback to work with, including lists that were created by community members to detail issues within the game. However, Kaivax also took the time to demonstrate how some of the bugs players were reporting were actually World of Warcraft Classic functioning as intended:
"Players reported that [the] Warlock demon summoning was broken - lots of players said that you shouldn't lose your current demon until the new one appears. We double-checked and in the original 1.12 WoW, and there, as soon as you started summoning a new demon, your existing demon disappeared. So the demo actually matched how the game played originally. There were a few other reports - such as 'rare mobs do way less damage' and 'Kobolds at Jangolode Mine run faster than walking speed when running away' - where we were able to confirm that the gameplay was the same in the demo as in the original 1.12 WoW."
That sounds an awful lot like Blizzard is intent on preserving some of the bugs that became part of the gameplay of Patch 1.12. Obviously, the developer will address any issues that actually break the game, as it pays to have World of Warcraft Classic be as accessible as possible given the niche demographic it is currently targeting. To that end, Blizzard also acknowledged that there are some bugs that will be addressed, such as Rogue Energy, Slow Fall, Critical Strike rating, and more.
One of the trickiest elements that Blizzard will have to navigate with World of Warcraft Classic is just how much of the game the company is willing to preserve. When fans of the classic experience talk about what they want, many of them are adamant that they want the newest offering to be an exact replica of what it was like to play World of Warcraft during Patch 1.12. Given how difficult life was for players in Azeroth at that time, that means there will be a lot of newer players intrigued by the prospect of World of Warcraft Classic driven away by how obtuse some of its mechanics can be.
If nothing else, though, Blizzard maintaining many of the bugs from the original Patch 1.12 should send a clear message to those who are worried about where the project is heading. To the best of Blizzard's ability, World of Warcraft Classic really does sound like it will be a return to simpler, grindier times in Azeroth, non-gamebreaking bugs and all.
Source: World of Warcraft Classic Official Forums