Message board cynicism is a poor excuse for bad business practices.
I did some freelance without a contract once and because I didn't have an agreement in writing I didn't have much recourse to tell them there'd be a charge for additional services.
A contract will never be a quick and easy solution to stop people doing a runner but you can at least limit the damage caused with one.
If your client ends up using your work, your contract is going to end up plenty enforceable.
If your client ends up using your work and you don't have a contract, don't expect to get paid this year, and expect a painful obstacle course of unreasonable support demands. They'll pay you eventually, but since you've reduced the worst case outcome to "amount we agreed on" from "treble damages and site downtime", they have every incentive to drag things out.