In a 500 mile PQ I sometimes had 15 start/end points in GE. Once I had all of them, I would export to a text editor, remove the headers and footers to make them all one path and request a PQ on that 500 mile stretch, whereas in Google maps I could have defined the route on the screen with no drama. I only discovered this after defining a 3800 mile route in Google maps and had to throw it away after I couldn't get a PQ with it.
I suspect that most of the people using kml files with Groundspeak are the more serious, higher volume cachers (and would hope that most of them are premium members). I would be willing to pay more than $3/month just to add that service back in. If I look at what I spend on gas/batteries/wear and tear on the car for a big day of caching, the Groundspeak charge is a drop in the bucket.
I think the feature that was disabled must be something I never used in the first place, lol, because the only thing I used the .kml files for was piecing together routes the way Sudonim described. I just logged in and it looks like that functionality is still available. In another thread TeamHorwich pointed out that gc.com is using the Google Maps API to allow routes with multiple points so stitching together files isn't needed anyway.
I don't know what KLM feature are you missing, but it is possible to view geocaches in Google Earth in realtime without making PQs.