The act of speedrunning is not bad.

The act of forcing it upon others in your group is the problematic part. When an i90+ tank solo que's and gets paired with say an i60 healer, i70DPS, and i55 DPS in Brayflox and decides to go pull EVERYTHING and dies, and then starts to blame EVERYONE ELSE for the fault, is where the negativity comes from (this is just one of many examples, such as three people queing together and then booting the 4th at the 2nd boss so they can leave scot free is another).

If you're gonna speed run, either
(1) find like minded individuals via PF
(2) analyze the group you are randomly paired up with and if they feel they can handle it, make your intentions known / suggest the idea of doing the Speedrun