I'm for keeping it. The speed is capped at 300, so you can't hit insane speeds with it. You also can't shoot accurately while moving, giving the other team an advantage if you overuse it. I think it's a decent balance between a good reward for playing on the servers often and not being too overpowered.
On 1v1s, as laytonu mentioned it doesn't give any advantage (except for knife rounds.) In Retakes, unless there's a ton of people shooting the hops always make that loud *thud* noise when you hit the ground. If you're using headphones, you can usually hear people from a mile away.
Edit: Not many know this, but you can also tell if someone's using bhop scripts by listening to the sounds. If someone's using non-server scripts, when they hit the ground after jumping on a flat surface, if it consistently makes the *thud* noise, it's the server scripts. If it consistently does not make that noise and it's the lighter tapping jump sound, it's a script or a cheat of some sort. While I don't think that in itself constitutes a ban, it can be an indication that the person has some other sort of script or cheat, such as wallhack or aimbot. If they're unscrupulous enough to have one, why not the other? This is why having the server bhop script is a good thing, if we didn't have it the cheaters who try to hide their cheats probably wouldn't use blatant scripts. Knowing they bhop hack gives us that extra bit of information on them.
Just my thoughts on the matter.
