"I wonder exactly how many are affected remembering the 6 month rule applies to most countries around the World anyway."
It will affect them as well, youngmaf.
Until this change you could apply for renewal up to nine months in advance and lose no validity. So, if your passport expired in December and you were planning a trip to a "six month" country you could travel on it until June. If you wanted to travel later than that you would have to renew. Under the old arrangements you could do so in March and the your new passport would expire on the tenth anniversary of the expiry date of the old one. Now if you wanted to travel in, say, August, you would have to apply for a new passport in July at the latest (to be sure of receiving it in time) and it would expire in July or August (depending on when the new one was issued) ten years hence. So, fully four or five months lost. For people travelling frequently the situation is even more tricky as they will have to fit in their renewal between trips and not have the flexibility they had until now.
I don't know of many countries which do not accept passports with >10 years validity and the government's explanation that they "did not want to see travellers stranded" is disingenuous. I don't think too many have been stranded so far when presenting a passport with more than ten years validity. Instead this is simply an exercise to screw even more cash out of travellers and it is being introduced on false pretences.