My own opinion is that overclocking, when done properly, can save a ton of cash and/or significantly increase your performance.
Think: I am planning my new build. I can choose a £40 CPU or a £120 CPU. The £40 CPU can be overclocked to beat the £120 CPU, with no extra cooling requirements. Yes, the £120 CPU can also be overclocked, but this way I save £80 and have the same performance.
It's not a cure-all solution, and it's certainly not for the inexperienced. However, I disagree that modern hardware realises less benefits from overclocking, IMHO it's at least the same, if not more. Are there any old CPUs that can manage over a 100% overclock? I don't know of any, but several modern CPUs are capable of this.
Also, remember that the opposite, underclocking, can be great to extend battery life and/or reduce heat.