It prompts me to ask who would want a PPL IR and why?
People who want to travel. Granted, the IMC rating lets you do this within the UK (although personally I don't think my IMC training was up to much...), but forces you to be at low altitude in uncontrolled airspace most of the time. Outside the UK, you're stuck without an IR. Any trips need to be planned on the basis that you may not be able to fly home.
Without an IR, a PPL is just for fun. With an IR, you can use your PPL for private and business travel. (Or can you....? If I'm honest, I'd have to say I'd rather sit in the back of a Boeing than fly myself home after most business trips.)