weird laundry faucet

I am replacing the laundry faucet in my grandmother's basement, but there is a slight problem. There is a 1/4" plastic line with a compression fitting that comes out of the back of the faucet and goes into the cement floor and I don't know what purpose it serves. This line runs continuously and is the reason I am replacing the faucet (standard, simple brass rough-in type faucet). It is a few feet from the floor drain and I am pretty sure I can here the water going down the drain. Is this line used to keep the floor drain wet? I've looked online and can't seem to find any faucets with this 1/4" fitting on the back. Is this important? (the house is about 25 years old).

any help would be great,

thanks.

plastic line is a trap primer and it is used to keep the trap wet as you surmised...
If you want you can install a regular faucet and just make sure you manually "prime" the trap once a week or so...
Alternatively you can install an automatic primer on one of your water supply lines...
The final option (and usually the one I recommend) is to pour some mineral oil into the trap (1 cup or so)... This forms a barrier over the surface of the trap seal (water) and prevents it from evaporating...
Adding a little water (a cup or so) every month or two should be sufficient...

install another faucet with a tapping.

the only reason you think it runs all the time is the faucet leaks and the primer is the easiest route for the water. best solution is to replace the cartridges and seats