I think this follows the 90/10 rule. Most of my work is on my own machine. Occasionally I will be on a server and attempt to use some configuration from my personal .vimrc but instead have to fall back to slightly slower methods.

The time lost in that 10% is totally worth the cost of the time saved in the 90%.

And since everyone uses their text editors differently, it's not practical to move any one individual's personal configuration choice into vim core.