At least in the UK, KLM seem to have increased the number of fare classes in the "Economy semi-flex" category. Now just two fare classes appear in the 'take off' fares category, one at 25% earning and the other at 100%.

So if you select 'semi-flex' from the boxes on the right hand side you will get the second cheapest 100% fare plus in an emergency your ticket is changable for a hefty change fee.

For example LON-AMS the cheapest 100% fare (ex tax, etc as the list down the side doesn't include this for the UK) is £52, the cheapest semi-flex fare is £77. This is a significfant reduction in costs for a ticket with any flexibility. It's a good move by KLM too as I'd happily pay a bit extra for some flexibilty (+ an easy way to get those 25% fares out my way) but wasn't willing to pay the prices they demanded before.

UPDATE: turns out it's not all working as good as it seems. Although it was working fine on Saturday, it now seems to consistently select the most expensive 'semi-flex' fare when you select that option. More bugs in the website I think

However, if you select the cheapest take off fares you can accept the websites offer to upgrade you to a semi-flex ticket and it will upgrade you to the cheapest one available. So the best advice for now is look for the cheapest ticket and if it's a 25% ticket then hit the offer to upgrade at the bottom, this will take you to the cheapest semi-flex fare which is the second cheapest 100% earning fare.