If it was legal, it would probably be vastly safer to acquire and use recreationally, so even if the amount of use stayed the same, the actual negative effects would probably decrease.
I don't have any stats for crack cocaine, but look up the effectiveness of diacetylmorphine maintenance programs in Switzerland and the UK - these are government-run programs in which heroin users are given access to pure, unadulterated heroin so that they can have steady day jobs.
Spoiler: These programs have been proven time and again to be effective in reducing crime.
Crack cocaine is biochemically identical to powder cocaine (the main difference is the means of ingestion, not the chemical compound). And I can assure you that many cocaine users hold very steady, very high-paying jobs (in certain industries more than others).
If the percentage of crack users who could both hold a steady job to pay for their addiction and also not significantly drag down those around them was > 90% (e.g. workplace accidents, parenting), then I could support ending the war on crack.
One of them is the drug itself, and since I am not familiar with crack (thank god), I would consider alcohol a good example. It's legal, "dirt cheap", and can utterly destroy lives with a completeness few drugs seem to be able to match. Everybody knows what alcohol can do, yet it still happens a lot (to put it mildly). So yes, making stuff legal and having information instead of disinformation is not a magical solution.
But that doesn't mean illegality and misinformation cannot make things even worse. Legality does affect price and safety, I think it's very hard to deny this or show otherwise (feel free to try). If a dealer sells rat poison instead of Ecstasy, it's not like the buyers can go to the cops about it, for example... and I'm not saying Ecstasy if safe no matter how it's used, I'm saying rat poison is harmful in all cases. And dealers are operating in the underground anyway, so they have little reason to care about adding on top of that. I'm not sure about "gateway drugs", but I am pretty sure about "gateway criminality" being a real thing, and it also applies to addicts, not just dealers.