Sprinting was added to Minecraft in Beta 1.8, along with hunger. While I don't like the hunger system, I don't think there's anything fundamentally wrong with it. Sprinting, however, alters the way you play the game in a huge way.
When you move 30% faster with very little penalty, or for a slightly larger penalty can effectively double your movement speed by sprint-jumping, you shrink the scale of the world from a huge environment to a small sandbox where you can decide where you are at any given time.
Sprinting also gives you a "nope"-card that you can play in dangerous situations. Instead of playing the game better (thinking about positioning, making sure you're prepared) you can simply... leave.
A nostalgia trip
Think back to when you first started playing Minecraft. For most people reading this, that will be well after beta 1.8. Version 1.2.3 was the version I started on. Think about how you played when you first started, before you knew all the meta strategies. Were you sprinting and sprint jumping everywhere? My guess is no. The gameplay loop hasn't actually changed all that much since then, but you have changed how you approach it.
No Sprinting
So, with all that explanation finished, what does this data pack do? Simple: it disables sprinting for survival and adventure mode players.
There's actually no way to disable sprinting in the game, or at least not one that you can do without mods. This data pack disables movement and jumping when you start to sprint and shows a notice above the hotbar.
When you're literally not able to sprint, it changes how you play, and very quickly walking will become second nature.
This is best when paired with No Sprint-Swimming and Expensive Boats, to make movement more intentional and distance more meaningful.
