Even if you think that making (certain) drugs illegal is a good idea, naming this the "War on Drugs", or calling for a "War on Drugs" above and beyond simply illegality, is a bad idea. This is because war is something that (generally) you win or loose. But it's impossible to a War on Drugs; it's impossible for the government to eliminate any sort of undesirable behavior, from jay-walking to murder. And if a War on Drugs makes sense in spite of this, wouldn't it also make sense to declare a "War on Crime"?

So, what's the problem with an illogical name/slogan? The problem is that it influences the way that people look at the problem. Rather than looking at drug use as something to be minimized and contained, like law enforcement does for other crimes, it looks at it as a problem that must be eliminated, something that must be won. Since whatever current efforts are being made don't work, why, pour more resources into it. And if that doesn't work, pour even more resources into it.

Also, war is a (hopefully) unusual state of affairs, somewhat like a drawn out emergency. The rules are different in a war: people get drafted, martial law can be imposed, foreign civilians are killed by collateral damage... With the idea that the fight against drugs is a war, some people are more willing to put up with negative things, like insanely harsh sentences for drug crimes and the loosening of requirements for search and seizure. In fact (this is from memory), Daryl Gates (or some other police chief) once claimed that drug users should be shot, because if there's a War on Drugs, then taking drugs is an act of treason.

So if you want to keep drugs illegal, come up with some other phrase for it.