Exactly: not having a fully de-iced twin, and not having a full IR, amount to a restriction in planning a flight which one applies to oneself.
The IMCR still allows more options than vanilla PPL in the UK - and the decision about whether to attempt any particular flight is, of course, informed by one's legal privileges, one's actual skill, one's currency, and the actual conditions pertaining.
Equally, more options would be available abroad with a full IR, but the IMCR is still valuable in the UK: less so if not kept current, more so with good currency.