Sorry to be dense but what do you mean "have the means to leave within the grace period"? I wasn't planning on extending because I have a 5 year permit and so I was planning to apply for ILR at the end of that time hence no need to extend or renew.
That's fine then. The grace period only arises when a WP expires or becomes invalid and the person does not qualify for another immigration status. It's 28 days. If you are converting into ILR it will not affect you. In 5 years time, you will apply under the new system being laid before Parliament this November.
Not everyone is as fortunate as you. Many have WP's expiring next month, next winter, next year, and so on before they will reach the residency requirement for ILR; and hence my concern that they will not be able to extend because their sponsor does not have a license.
Since you're not in that population, I have to ask what you were worried about in the first instance?