I agree that it would be really hard to challenge a tank fight around different classes. Which is why I said it was stupid to have all tanks have the same challenge, I understand that it is typical blizzard laziness but it was too much. But I disagree to the extend that burst didn't play a big role in the fight, especially phase1. The amount of internals were a joke when I did it on DH but it was a big deal especially for specs like blood with low mobility. On top of it all, if you had too many internals that die and respawn at different spots, their kiting patterns were completely different and they would roll over the retarded velen in that fight and kill him which was annoying as hell.
but I also disagree that the tanks secondary role is "to do damage". This is one of those myths that came up from the player base sometime around wotlk and cata and it stuck, no matter how much blizzard tries to destroy it. I mean they completely removed vengeance and seriously tuned down tank damage but people still believe tanks are supposed to do damage for some reason. They boosted tank damage a bit for legion tank artifact leveling and it is the last tier of every expac with the usual gears inflation so that tanks are serious damage for sure but on early tiers it is not the case and not their role. End game pve is balanced around 20 man raiding and even in the current tier, the fact that the tank is doing 500k-750k dps or 1M to 1.2M really doesn't make a big different when all dps is doing +2M each. What I wish they would being back is tanks that are actively helping the raid through buffs and CDs which was their actual secondary role for some time. Blood DK talent buff in wotlk was an amazing single target buff that a tank could give to top dps for burst or Bears that could buff and give an extra buff to a player in raid as well as cata last tier set bonuses that extended the individual CDs of a tank to the group was pretty awesome.