Is your Sprint ability broken or something?

Every job I play has the same skill on num 5 (MMO mouse) and it will stay there till my dying day.
Sprint is incredibly useful.
As a tank I can mitigate damage while pulling, as a melee I can continue dps mobs on the run far better and get into position faster, as a SCH/ WHM I need to be in melee range for my aoe, as an AST I can get positioned for Divination faster, as a caster I can cast & run during pulls while still keeping up (before any tank main explodes: yes, yes, I'm watching my aggro, I won't mash it till it turns red mid-pull) and as BLM specifically I can get closer to the boss/ mobs where it's generally easier to dodge mechanics while staying in my Leylines.
Even on the incredibly mobile DNC I regulary use it to get into melee range faster for aoe.

I won't run ahead of tanks to pull if they don't use Sprint but it's such a useful skill I generally use it on CD anyways. If not to keep up with sprinting tanks than definitely to position myself faster. Being able to clear a dungeon without it or not is irrelevant. You can clear a dungeon without a great many skills but using them is still a benefit, e.g. Tactican/ Troubadour/ Shield Samba/ Mantra/ Nature's Minne in big pulls, selfheal after being specifically targeted by a mechanic, using dmg buffs on big pulls etc.

I'm guessing a lot of times situation 1 feeds into situation 2. Tank sprints ahead; no one in the group sprints to keep up; tank dies because he's soloing the entire dungeon for 20 seconds. End result is the tank stops sprinting in future dungeons, and does the pull really slow to make extra sure everyone has a lot of time to assess what's happening.

I personally by default do small pulls in PUGs anyways. I don't like having to rely THAT heavily on everyone else to be paying attention.

I personally don't like using Sprint during pulls because of the weird server tick issue it has where it is an oGCD, but it won't always activate when you try to weave it in, so you have to basically waste an entire weave window on just sprint I'll use it in e4s if I get unlucky with how certain mechanics decide to play out, but other than that I don't typically need to use it.

For dungeons I'll use it if the tank uses it so I can keep up.

I actually get more frustrated when BLMs don't use their teleport ability to stay with the group between pulls in a dungeon.

But if they want to stand in the hall and miss Tech Step that's their business, I guess.