Why the new Minecart speed should be 16 blocks/second

The four primary methods of transportation:
 
1. Horses
2. Minecarts
3. Elytra
4. Boats on ice

We can further divide these:

Class A: Complete freedom of movement compared to class B. But these can "die," lose durability, or need upkeep. Think horses & elytra.

Class B: Significant collecting of resources and building to use. Movement limited to tracks/ice. But once it is in place, it won't die or lose durability. Think minecarts & ice boats.

While the pros/cons almost balance out, class A will *always* edge out class B methods due to convenience/no movement limits. How can we balance? A slight speed advantage to class B.

Late game: this system works perfectly. Ice boats allow 40 bps & 72 bps w/ blue ice. Rocket boosting with elytra gets 33 bps, just blow ice boat's 40 bps, thus putting them into equilibrium.

Early game: Minecarts get 8 bps while AVERAGE horse gets 9.49 bps (fastest getting 14.23 bps!) We can see the problem here. The advantage horses have over minecarts is not negated but *increased* by the slower minecart speed. So, many players are tempted to just skip over building a railway and ride the horse until late game. 

16 bps puts the minecart a little bit above the speed of a consistently good horse just as ice boats are a little bit faster than a consistent elytra speed.

In the Legacy Console Edition, minecarts actually DID travel 16 bps and this system worked perfectly. Players did not stop using horses, but rather both became equally good options for moving about the world.